So, you've read through the basic strategy page for Settlers of Catan and are thirsty for more? Well, then you've come to the right place. I'll start slowly again, with the more general and useful advice, and then move into more specific areas.
1) Count your cards, name them one by one - This is a simple strategy, but very hard to carry out unless you have an amazing memory. Basically, you should always keep track of what cards people get every time the dice are rolled. Make sure to not be distracted from this even when you get resources from the dice. Also, pay even closer attention to the trades being made and offered, as those will tell you what strategies your opponents are carrying out. With this information you can identify when someone is close to building something they need and warn others away from trading with them. You can also use the robber more effectively and make more informed trade offers and acceptances. While you don't need to keep track of every card every player has, you should at least be paying attention to the strategy each opponent is using and when they are close to building a new settlement or city.
2) Seven - Seven is a key number in this game. Once a player has seven victory points, they are much closer to winning the game than the number suggests, especially if they don't yet have longest road or largest army. The reason for this is once you have seven victory points, you are generating resources at a much faster rate than you were initially since you have more settlements and probably at least one city. This increase in resources decreases the amount of time before you can build more settlements/cities. It also means it is easier for you to divert resources to building the largest army or longest road, and it means you are less likely to trade with others because you are more self-reliant. If someone has seven victory points and doesn't have largest army or longest road, they are probably 2-3 turns from victory because all they have to do is build one more city/settlement and grab one of these. I make it a personal policy to never trade with anyone who has seven or more victory points if they don't have longest road or largest army (unless I am in the same or a better situation). I also suggest players never get to seven victory points while having longest road or largest army, since it makes others focus the robber on them while they are actually still a few turns away from winning. The one exception to this is when you are in strong competition with another player for one of those two awards, and need to start investing in it from the start of the game. Seven is also a key number because you should go through great lengths to make sure you don't end your turn with over that many cards in your hand.
3) The Portrait of Development Cards as a Bad Idea - We've all bought our fair share of development cards, hoping to get that elusive +1 victory point, or maybe a monopoly, or even that last soldier to get largest army. However, most of the time we are disappointed. In my opinion, you should stay away from buying development cards unless you are going for the lots of cities and largest army strategy. I will break it down numerically in a second, but basically they just aren't worth the amount of resources you put into them on average. Here is the breakdown of your chances of getting a certain development card, assuming a fresh deck:
Road Building: 12%
Year of Plenty: 12%
Victory Point: 16%
If you get a soldier and you are not going for largest army, this card is definitely not worth the three resources you just spent, two of which could be used to build a city for more production and resource points. If you get a monopoly and use it well, then it was worth the three resources you used. However, this only happens less than 12% of the time because you need to not only get the monopoly card, but also time its usage right. (On a side note, if you do get the monopoly card, consider trading away a lot of one resource you have, then playing the card to get those resources back. Be prepared for a lot of angry friends if you do this). Road building might also be argued that it is worth the investment since 2 roads equals 4 resources, which is more than the 3 you just spent. Also, roads are probably hard to come by for players focusing on the ore/wheat path to victory. Again, though, the chances of getting this card are very low and you are better off using your resources to build your own roads. Year of Plenty may also be worth the three card investment, assuming you use it to get resources that you have no access to. If you are playing the middle road strategy, however, this card is much less useful. Also, just like the previous two cards, the chances of getting this are so low you would be better off trying to trade or use a port for those two resources you need. Finally, victory points are the best thing to get. However, this is just a 16% chance per card. That means you would need to spend 12 resources on average (see the math behind this brought to you by phantom042 here) to get one victory point. Obviously, this is a far worse choice than just building those roads and settlement, or building that city. Both of those options also increase your productivity as well. So, overall there are some beneficial development cards, but your chances of getting them are very low and it is almost always worth it to invest your resources elsewhere. There are only three times that I see a development card as a good investment. First, if you have a lot of cards in your hand over 7 and need to dump some but have no other options of what to buy. Second, if you are trying to win by the ore/wheat strategy. Third and finally, if a lot of cards have been bought already and the vast majority of them have been soldiers. This means the probabilities of getting a card you can use are more in your favor (especially to get those victory points), and it may be worth the three resource investment, especially if you are using the middle ground strategy.
4) General shiftyness – When decent behavior and standard tactics fail, it's time to shift to a different gear. One which some might consider a tad on the Dark Side. Tell you what, though. I'll describe these strategies and you can resolve your own moral dilemma regarding them. One thing that I love to do, and am consequently always paranoid that others are trying, involves the monopoly development card. When you have this card and are deciding whether or not to play it, a great idea is to test the waters and see what other people have. Offer trades for different resources, even trades which you actually can't do. The point of this is to get players to reveal what resources they have and how much. Then, with this information you can decide whether or not to use the monopoly card and take whatever resource people were just offering to trade you. If you are counting cards you can spot when someone is using this strategy when you notice them offering a trade you're pretty sure they couldn't do. Another sneaky thing to do in this game involves the robber. Hopefully you are doing well now in games. However, this probably means the robber is getting placed on your settlements/cities more and more. I'm not a fan of that, so something I like to do when someone is considering placing the robber on me is to remember what resources they are looking for and see if I have any in my hand. Hopefully I have nothing of the sort, just a lot of junk, like three sheep. If this is the case I will show my hand to my opponent, letting them know that if they put the robber on me they won't get anything useful out of it when they take a card. If they still do place it on me, they are also more likely to take a card from a different player on the same tile. You have to be careful with this strategy though. It can backfire if you miscalculated what your opponent was looking for and they actually desperately needed sheep.
5) Advanced placement – It's time to once again discuss the ever-important initial placement of your two starting settlements. If you haven't already, check out the guide I wrote on this topic and then come back here to read some more. There is a habit which I see many new players practice, namely placing one of their two starting settlements on a port. Don't do that. Or, I should say, try to avoid doing that. The reason is you get far less dots by placing there, and unless you are landing on a 2:1 port which you have at least 9 dots on at the end of placement, you will be very slow to expand. Placing on a port limits not only your productivity early in the game, which is crucial to success unless you're lucky, but it also means you have less good spots to expand to. Think twice before doing it, even if you are taking a 2:1 port away from an opponent which would otherwise help them out a lot. This brings me to my second topic in this section: using initial placement to hinder your opponents. It's mean, I know. It's even down right evil at times. As such, you should probably avoid doing it. When placing your initial settlements you should focus more on what placement helps you the most, than what it does to your neighbors. If the placement happens to block them from expanding to someplace they were planning, then all the better, but it's not worth a worse initial placement to accomplish this. It's in early expansion where you can really stick it to your opponents, robbing them of the spots they had been looking to expand to themselves. Another thing to consider in initial placement, if you are going for longest road, is whether or not your second city you put down can be easily connected by road with the first. This usually isn't that important, but if you notice that another player is gearing up for a longest road race, it can be a deciding factor. Connecting your two starting settlements means you have to pay 1 brick and 1 wood less to get longest road, and it also means that you can have a road 15 segments long. Normally a player's two settlements are separated for the whole game. This means that one segment is lying uselessly in some corner of the board and you only have 13 more you can place, making your maximum road size 14. This situation rarely occurs (I have only seen it twice so far), but it is something to consider when placing your second settlement if you're going to try to get longest road. The last piece of advice I have on this topic is to try to diversify the numbers your settlements are on. While it is awesome to have settlements on 6's and 8's, if you have both starting settlements on 6's then you are taking a big gamble. If a lot of 6's are rolled, then you're going to do great. However, if none are rolled, then the game will be very boring for you. To ensure this doesn't happen, place on a 6 and an 8 if you can, and make sure to be on 5 or 6 different numbers to start off with. Otherwise, you might get a turn of bad luck and miss out on that crucial early expansion piece.
6) Cops and robbers - Okay, it's that time again. You've rolled a seven, and you need to figure out what to do with the robber. Right now he's on one of your cities so you're glad to get him off, but you're winning the game right now or there is no obvious leader. Also, the earlier advice I gave still isn't making the decision clear to you. Well, here are a few more tips that might help. If it is still early in the game (everyone has 2-4 victory points), consider putting the robber on the desert. This will make you friends with everyone and also make sure no one holds a grudge for that time when you put the robber on them and the number he was on was rolled 8 times in a row. Let's say it's later in the game, though, and there's still no clear leader or you're the leader. It's your turn and you roll a seven. Do you place the robber on a 6 or an 8 which a couple of opponents are on, or do you block the largest source of brick in the game, which has been extremely hard to come by so far? Well, I usually opt for nailing more than one player at a time. Partly because it is more fair and partly because it prevents a single player from feeling threatened by you. And if that single player isn't winning or isn't competing with you directly in some way, then you should probably just try to stop the most amount of resources possible from falling into your opponents' hands. Alternatively, you could place the robber on a spot which would help your opponents the most if it is rolled. For example, your opponent wants to take Longest Road away from you, but only has access to brick through one tile next to a city. Even though the number on that tile is low (2 - 4, or 10 - 12) it might be worth it to block, ensuring a dearth of brick for that player. Now, I've been focusing a lot lately on what to do when you are moving the robber. However, odds are most of the time you will be on the other side of the robber, cursing him as he steals from your settlements and cities which have worked so hard to gather resources. Apart from wallowing in depression over this ill-fate, what can you do? Well, the best thing is to play a soldier card or roll a seven. However, both of these are pretty unlikely so just let it go. Don't let it distract you from your main goal. Don't start investing in development cards just to get it off unless that spot being opened up immediately is the cornerstone to your victory. It will move eventually, after being satiated off the fat of your land. If you feel particularly nasty, do something to hurt whoever put the robber on you (keep it in-game though).
7) Miscellaneous Advice - At this point I've got the main strategies covered pretty well. However, I have a few smaller pieces of advice left which should come in handy:
When expanding early in the game, do so using the following additional priorities on top of the ones mentioned in the basic strategy section: First, try to go for the spot with the most dots, second try to increase the diversity of the resources you produce, and lastly try to get to a nearby port.
Try to buy something every turn. At least make sure you never end a turn with 6+ cards in your hand since you will probably get over 7 before your next chance to use them. However, if you're just one resource away from getting a city or settlement you've been trying to build for a while, then ignore this advice and take the chance you'll lose half your cards.
Look for every combination of cards which will give you what you need to build. This is accomplished most importantly by remembering which ports you have access to. For example, if you have a 3:1 port, 1 brick, 1 wheat, 2 sheep, and 2 stone and no one will trade stone for wood (which you need to buy that settlement you've been working on for the past 4 turns), then remember your 3:1 port. Try trading that extra sheep for a stone and convert the three stone to a wood. Or, you could even try trading the two stone for two sheep and trade the three extra sheep for a wood.
I put this last of all advice because it is very important and I want you to remember it. A great secret to doing well in Settlers of Catan is to keep a low profile. When you build something new don't loudly announce it to the world. Constantly point out when someone else is winning or doing very well. Keep the focus off yourself by being kinder-than-normal with the robber. This will hopefully keep other players from early notice of when you've hit seven victory points and are geared for victory. It will also usually keep the robber off yourself more than you would think.
Well, that's it. Hopefully these strategies have given you some additional ideas as to how to win your next game of Settlers of Catan. Feel free to post on the forums (which I check regularly) if you have any comments / criticisms / questions, or even a new strategy I don't have listed here. Also, you can check out the alternate rules page for some interesting variants on the game, or the links section to see some additional Catan resources and even find where you can play the game online for free.