IMO people make painting stuff sound a lot harder than it really is..
Here's my "system" which is pretty much universal for all paint types, stains, urethanes, etc.. And it works for painting anything.
- prep - the most important. Sand, clean, and just because it feels smooth doesnt mean it is. If you dont really feather out your bondo well, it'll show later.. And make sure it's clean and rinsed and dry.. Dont rush this.. A good finish is 9999999% prep work (give or take 9900000%)
- thin the paint. If its water-borne enamel, with water. If latex, with latex conditioner (floetrol), if oil based, with thinner. I don't know what to thin Kilz with - floetrol causes some kind of crazy reactino that makes it into rubbery goop right before your eyes. Make it thin thin thin so you get thin coats, and orange peels will flatten themselves out more while it dries.
- roll on the paint with your foam roller (or good brush), and while its still wet, get a dry roller (or good brush) and "knock down" the paint. You arent spreading color at this point, but flattening it out, and sucking up all the little ridges. Really good quality brushes can create a better finish than foam rollers in the right hands, though rollers are probably easier for the noobs.
- I only sand between coats if I really want a super smooth finish I can comb my hair in, or if its particularly rough. If you knock the coats down like I mentioned before, it's not as necessary.
- after about 9.3 bajillion coats (or 3 or 4 or whatever) I might lightly wet sand with really fine paper - like 400 grit - if it looks a little splotchy, just to smooth it all out. It doesn't have to look perfect, thats what the rubbing compound and a clean t-shirt and elbow grease are for- rubbing compound is essentially like 10,000 grit sandpaper. Follow the directions on the can, and always test in an inconspicuous area.. Buff with a soft towel, or whatever.
The glossier the paint the more work you need to make it look good. It's really not that hard, it's not like you're putting a showroom finish on a porsche, you're just painting a plywood box.
My advice to original poster is to lightly sand, add a few more coats, and buff/polish/rub the finish out.
(Or laminate it, I'm sick of painting things)