Sounds like you are not aggressive enough. The beauty of aggressiveness is, sometimes it can force your opponent off a hand that has you beat. Also, being aggressive and betting gives you information that check calling would never give you, like a range of what hands they might have. If you check call, they can have almost any hand.

Position is also key, raise more from late position to steal the button. Then, if everyone checks to you on the flop, get in the habit of betting even if you don't hit (with some exceptions, if you got a draw and wouldn't mind seeing another card, do that). It is amazing how often you can take down a pot just by putting a bet out there. Also, get good reads on your opponents when playing. If they are loose and very aggressive, let their aggression come out, then trap them with a big raise when you are sure you are probably ahead. If they are passive, then you will have to be the one to take the initiative.

There is alot more to it, but it's a good start. I reccomend jumping into the discussions, and posting hands here, it will seriously help your game out to see where some leaks are that you might not know about.

Good luck!