You should also mix up your strategies based on the flow of the game to keep your
opponents off balance. For example, if you have check-raised the same opponent a
few times in a row with a strong hand, you might try betting out the next time. He
might then suspect that you are on a bluff and may play back at you. On the other
hand, if you have bet out a few strong hands several times in a row, you might want
to check-raise. 
Another tiling to be aware of is the different moods of your opponents. An
opponent’s mood can change his playing style so always be looking for changes,
this is especially true against regular opponents you play often.
Playing your opponent is an important skill to raise your game to an advanced level.
Poker is not meant to be played using a formula. Observe your opponents and
recognize their strengths and weaknesses so that you can use this knowledge
against them. Knowledge equals opportunity!