Good Introductory Strategies for Steam
You need to be planning a way to build up to routes of various lengths, up to 5 or 6 long, from the very beginning of the game.  Look at the resources on the board and route them mentally to places that are far away, then fill in where you need to place tracks.  Realize that resources near other cities of the same color are probably going to go away before you complete the longer routes.

You might eventually need Urbanization to help you build the routes you want.

A lot of new players will "land grab" the routes that give immediate gratification but then realize they don't really have a good growth strategy thereafter.  Don't worry if your start is slightly slower than such players, although you definitely need to get some goods delivered early.