Don't expand too quickly, you'll kill your economy. Civ III encouraged you to grow as fast as possible so in Civ IV they put in maintenance costs to stop that. You've got to be careful in your expansion.(Original post by teshla^^)
Na i love turn based games.. Medieval 1 and Rome are my fav games...but this game is too in depth. Whats the best tactic? To create new settlers and just build settlements willy nilly or create loads of workers and build farms and roads etc so that my trade increases and my capital becomes a fortress?
Have a look at CivFanatics and Apolyton. Two decent fansites with plenty of advice, especially on the forums.
All you need to know is here