Like all mathematical problems; and make no mistake, poker is a mathematical problem; you need a solid poker theory on which to base your decisions. Fortunately a basic poker theory has already been developed by David Sklansky:
Every time you play a hand differently from the way you would have played it if you could see all your opponents' cards, they gain; and every time you play your hand the same way you would have played it if you could see all their cards, they lose. Conversely, every time opponents play their hands differently from the way they would have if they could see all your cards, you gain; and every time they play their hands the same way they would have played if they could see all your cards, you lose.
From this theorem we can deduce two facts:
First, there is a right and a wrong decision for every situation you’re presented with at the poker table.
Second, you profit by making the right decision and tricking your opponents into making the wrong decision.
So poker theory dictates that deception should play a major part in your poker strategy. The question that poker theory leaves unanswered is, “how much deception and how often should you change gears?” Unfortunately there’s no right answer to that question and that’s why there’s so much variation in poker styles.
A generally accepted idea is to introduce a random influence to your poker game. Dan Harrington, for example, recommends that you use the second hand on your watch. If you want to raise pocket 9s from middle position 20% of the time and call with them 80% of the time, just glance down at your watch. If the second hand is between 1 and 48 seconds, you call. If it’s between 49 and 60 seconds, you raise and the beautiful thing is that your opponents can’t read you even if they know what you’re doing!