Study tactics...but try and be a complete player.
How To Be a Tactical Player

Play tactically! Look for forcing moves and try to calculate harder. There is nothing mysterious about it.
How to calculate harder?

I think another way to say what chessmicky said is if you find a good move, great! But before you play it look for something better. Or maybe when you find a good move, make sure you didn't over look something. This happened to my opponent in my last online game. My opponent countered by attacking my queen after I attacked his. His last move wasn't forced but at first glance seemed natural and "decent" but if he looked a little harder, the consequences if that move would come at a high cost.

Perhaps I should have said: Look at every forcing move; Every check, every capture, every threat. Calculate them out. This is how you will find tactical opportunities, this is how you will become a more tactical player.
Also, don't be afraid of losing. If you see a tactical opportunity, even if it seems risky, calcuate it out to the best of your ability. If it looks promising, go for it! Sometimes you will miss something, and you will lose. So what. Every loss is a lesson. If you are afraid to lose at 1500, you will never see 2000
Thanks a lot. My new motto is: Be careful yet fearless.
How can I be a tactical player?