You appear to be less of a threat when you have less points showing, but hidden victory points from development cards. Overall, this allows you to control the game and keep your plan a secret since your development cards are hidden. With this strategy, you control the game by directing the robber around the board with your soldiers and surprise everyone with victory points, monopoly cards, and road building. This is the best general strategy in the game, but can be defeated by the port or wheat monopoly strategy if the board greatly favors them. You’ll also want some brick and wood to build your first two roads and third settlement. The idea here is to get as much ore, wheat, and sheep as possible, but an equal-ish share of each so that you can buy tons of development cards. Also, make sure you have at least two road segments of a lead over everyone else to make it hard for them to steal it from you and build a settlement for every two or three road segments so no one can build a settlement on your road to break it. The keys to succeeding with this one is getting tons brick and lumber early, but then expanding to places where you can get wool, grain, and ore for the late game. You can usually get to 7 points fairly quickly with your 5 settlements and your longest road, but you need a plan to get those last 3 points. It works great in the early game because you can expand quickly and cut off your opponents from the spots they want but the challenge is staying relevant as the game gets into the later stages.
This is the easiest strategy for a newbie to use, but the more I have played Catan, the less I like this one.
Here you just want as much brick and wood as possible, so you can expand and build settlements. Check out the video version above or the text version below. I am assuming you know the rules and will just jump into the strategy. This is a primer for The Settlers of Catan that will cover the high-level strategies and specific tactics you can use to improve your play.