Every decision you make must take into account your position.

7,8 off suit is a horrible hand to call in first position, whereas if you're on the button or in the small blind, its not that bad of a hand if no one raises. Also position is very key if you are on the button or in the blinds when you want to steal the blind. This is one of the best ways to slowly add chips to your stack. But be careful, you never want to bet into someone. Make sure you have at least a mediocre hand in case he/she calls you.

Also you have to read the table to understand what is a good enough bet so that no one will call on a limp. You don't want to make a complete bluff and move it all in in case he/she is holding a high pocket pair. So make a bet that is enough to make them think, but also if you are re-raised you can fold with out being dented to bad.