Read NLHE T&P. Sklansky has a whole section on making mistakes. Your supposed to make mistakes, in NL you can't not make mistakes. It's about making your opponent make bigger mistakes. For example, If you get HU against a known calling station that will call any bet 100% of the time(exaggeration to prove a point) You would never bet the flop, or turn, and when you have a good hand, push the river. Sure it's mistake to not bet the flop but your opponent is making a bigger mistake. It's about your opponents mistakes and the advantage you take when they make bigger mistakes. If you need me to get a more detailed answer and quote Sklansky himself, I will but hopefully you get the idea.