Help with improvement

Hi, I've been playing chess for a while and now I am studying and trying to become better. Any tips? 

Have you found the 25 free Chess Mentor courses?  Sure chess.com is trying to get you hooked, but they're really well done.  Did I mention they're free?

http://www.chess.com/blog/webmaster/free-chess-mentor-courses

I improved from 962 U.S.C.F. in August 2013 to 1588 U.S.C.F. now. And the most important part of that was playing better players. In my last 30 tournament games, 22 were against higher-rated opponents, and probably half of those were 200+ above me. Challenge yourself. It might be a while, but eventually you will start winning against them. I had my breakthrough when, as a 1381, I beat an expert at a tournament. If you keep at it, through all the losses, your game could improve a lot. Another thing is to play standard time control games and avoid taking quick chess too seriously because in the end, it is not real chess.

Im going to a tournament next sunday, there will be really tough people, like some of the best chess players of my island