For keyboard, I rely soley on my ear (which in most cases when learning something new is trial and error). Sometimes, I'll use some chords that are posted, but usually I'll add my own little flavor to it if I do.
I do, however, know the basics of reading music. I played alto saxaphone from elementary to highschool, and I aslo sang bass/baritone in the highschool choir. But, I can only sight read single note at a time music. I am not trained and practiced enough to sit play sheet music for piano yet. But that is one of my gols though.