Settlers of Catan strategy is reasonably simple but with very subtle nuances that can only be appreciated with experience. However if you read up on strategy and take notice of what things work and what things don’t when you play then you can improve your skills very quickly.
Broadly speaking there are two main strategies. The first you target brick and wood, look to expand your road network quickly and build up more settlements. The other strategy is to target ore and grain and get two cities up and running as quickly as possible and then expand from there.
Neither of these is better than the other. It all depends on what the board looks like, when you are placing and what your opponents are trying to do.
Read Your Opponents
Key to improving your skills at Settlers of Catan is to pay very close attention to what your opponents are doing and thinking. It is not enough to just exist in your own little bubble. In order to make the robber and development cards most effective you need to have a good idea of what your opponents have in their hands.
You also want to be reading their minds in terms of strategy so you can cut them off if you want. Another good thing is to deny trading a particular resource to a particular opponent if they can’t get it. Even if they offer you a good trade you gain more benefit by denying them.
Every trade is an opportunity for you to get one over your opponents or for them to get one over you. Every time you need to think hard about who benefits the most. You may really need the resource they are offering and you may have an abundance of what you want to give away. But what gain will they reap from getting your resource.
For example you may desperately need a wheat and have five sheep to give away. But if that sheep allows your opponent to build a settlement where it cuts you off then is it really worth it? Potentially not.
You just need to be aware of these things and make every trade work for you, not your opponent.
Your Starting Roads
Initial roads are key to getting off to a fast start. Many rookies however make the mistake of pointing their road int the direction of the best nearby spot. However they often find that someone else will build there and the road will become redundant.
It takes a bit of a judgement call but often it is better to build towards a weaker spot.
This means you will actually have space to build new settlements, even if they are not as attractive. But it saves you having a redundant road and being down two resources before the game even starts.