Try looking up Koishii’s PYO tutorial! It’s really fun, and because you’re diluting the paints with water, there’s a lot less danger of layering them up too thick and losing details. A caveat: as Nam has pointed out, acrylics can get fussy if diluted too heavily with water, and may later flake. But I figure that when one is starting out and really just learning as one goes, it’s not such a big deal. And thinner paint means easier to paint over with less detail loss, if you decide to start over. 🙂
I’ve got three PYO’s in the works right now, and a fourth just about finished. The two griffins are being done with paint diluted with acrylic medium; the dragons are done by Koishii’s tutorial. There’s a big difference in how thick the paint goes on when it’s diluted with acrylic medium: clumsy me has trouble with it filling in the details, and I’m still learning how to prevent that from happening. I had a much easier time using Koishii’s tutorial.
Good luck! It really is a lot of fun! 😀