first post.

Work on the middlegame. Some useful books are John Nunn's move by move, the mammoth book of chess games, and Nimzowitch's My System (a classic). If you want to study some openings that's fine but don't over do it, or your play later in the game will go downhill. You also might want to get an end game book. I have Dorevsky's Endgame manual but it's advanced for a player of my level and probably extremely difficult for you to understand, so I would start with one aimed more towards club players or beginners. 

It's hard to overestimate how worthless opening study is when you're just beginning.  It is useful after a game to look in an opening database and see what the usual sequence is out to 5-7 moves or so.  But opening books wont do any good.

The main pillars of knowledge, and in order of importance IMO will be tactical patterns, middle game strategy, and endgame strategy.  The primary skill will be analysis (calculation and evaluation of the imagined position).  The primary method of improvement will be playing tournament length games and going over them with a coach or stronger player.  Books (middlegame or endgame) are useful too.

My $0.02

Don't be afraid to play the better players at your club. You will most likely lose, but if it's knowledge you want, the way they play will help, especially if you recently started playing.

Good luck!