Fast play high pairs and very strong hands before the flop. This puts more money in the early pot and encourages weak and garbage hands to fold that could get a lucky flop and beat you.
Don't draw to the low end or both ends of a straight. If a 9 8 7 flops, you want to be playing the J 10 and not the 6 5 or the 10 6. (The low part is commonly called the 'ignorant' end of the straight).
Unconnected Medium and Low Cards are Usually Unplayable. This includes suited cards that can't flop a straight. Both ends of a straight such as 9 5 fall into this very weak category.
Play starting low pairs cautiously. 66 down to 22. Usually not from an early seat and from the late positions, only when the price is right. If you don't flop a set or quads you should usually fold.
Play aggressively when you have a 2 way draw after the flop. If you can make a straight and a flush or trips etc., usually bet/raise your hand.
Bet an Ace or 2 high over cards after a garbage flop (a 3 suit 'rainbow' with unconnected medium and low cards). Usually fold if someone raises.
Watch out for uniform flops, like 8 7 6, they can easily turn into straights that can overtake your high pair or other good hand.
Check the raisers chips. Players that are close to all-in often rush the betting just to get all their chips in a sink-or-swim last hand.
Beware of Suited Flops that can make a completed flush. In this case, you should usually hold the nut in that suit, or have trips or 2 pair that can fill up.
Get caught bluffing once in a while. It is a way to vary your play and not be too predictable. You win pots that you don't deserve when your bluff works. You lose a few chips when it doesn't work but it will get you calls from weaker hands down the line when you have a strong hand and need the action.
Study your opponents, especially when you are not playing hands and can pay careful attention. Do they find more hands to play than they fold? Do they bluff? Can they be bluffed? Do they have any 'tells' (give away mannerisms) that disclose information about their hands etc.