"If your not betting your losing." That is a simple yet elegant way to sum up Nl limit holdem. When playing this game of skill, aggression is key. It is foolish to display blind, wreckless aggression. However controlled and calculated aggression is encouraged. You may ask, "What am I talking about?"
I'm talking aout playing your hands with confidence. This confidence comes from good or premium starting hands. A calculating aggressive player rarely checks and calls. This is the winning combination: betting, raising, and good starting hands. You must also know when to fold.
To explain, by betting and raising you make it expensive for players to get lucky on their draws. It's hard to call a pot-sized bet with a draw and just plain stupid to come over the top. It's your responsibility to make them pay to see if they can get lucky. Sometimes they will hit and you'll lose. The main point is that you played sound, aggressive poker, and over the long haul you will come out on top.