Practice Practice Practice and even more Practice. Just when you think you practiced enough, practice some more. I am in the same boat as you. I primarily play in Eb, but sooner or later you have to force yourself to practice in other keys in order to learn them. The best advice I can give you is to take what you know in Ab and then translate that to the other keys one by one. Learning your major scales in every key is also very important. So if you play a chord in Ab like this, Ab-C-Eb, take that up to A, A-C#-E, and keep going. If you have to sit down with a piece of paper and write each chord out to transpose it to other keys then do it, IT HELPS. Trust me on this.
