If you want to become familiar with music theory, (which I recommend) the best scale to learn first is the major scale. It's a good scale to learn, and all traditional music theory is based on and compared to the major scale. It's a beautiful scale when played expressively, and is easy to get used to. My advice would be to learn it inside and out. As many different scale patterns and locations of the major scale you can find. You'll probably recognize the sound... it's do-ra-mi-fa-sol-la-ti-do. So start there. Good luck, man.