Originally Posted by Ade Beats
If you are starting the best thing to do would be to learn triads - those are chords within a key - it will open a world of possibilities for you. You'll be 10 times stronger in composition, trust me and then learn chord progressions which will make you 15 times more..
This, and I can't speak to it's efficacy because I just started, but if you're already familiar with chords and music theory, grab a piano book of any general style you want to emulate or get a bunch of lead sheet and have at it.
Currently learning some Gospel piano goodness.