Base coat, sand, base coat, sand, main coat, sand, main coat, sand, main coat, varnish, varnish
That's my process, did it with rattle cans. Used grey base coat, matte black for the main coat, and a satin varnish for the finish. Sanding started as a heavy grit at first and getting finer each step after, going slow after the paint cured and using tack cloths to wipe the sanding dust after. Didn't sand the last coat, added two even coats of varnish at the end. All told a couple dozen cans, (32 I think... Don't remember but it's in my thread). All said and done, I estimated my paint job coat well over $400CDN in supplies, plus time, not sure if that counts my paint booth. I wanted the best finish I could. It was my first attempt at doing this, like ever, but I took the time and money to research and do it to my standards.
You could go cheap and roll on. I'm very happy with my finish. Wouldn't change a thing.
Your art will stick better the more glossy it is, but you shouldn't have issues of you just get a decently smooth and clean surface.