Yasser Seirawan's book on tactics was great, it covers most of them and explains the idea behind each tactic without using too much notation. I think it was the first book I read (Simply called Chess Tactics or something).
Bruce Pandolfini has a few good ones too. I'm reading one right now called "Kasparov Tactics" or something similar.
the one for your level is Back to Basics:Tactics by dan heisman (great duo with polgar's book) and 1001 winning combinations and sacrifices by reinfeld.
All you need right now is TACTICS and some basic strategy.
You could get a nice little magnetic travel set, like this one, to follow along with something in a book if you can't follow along in your head.