I don't think you're doing it wrong, per se, but I think you might be doing more work than you need to. If you're getting peel or cracking you definitely want to take the time and sand it down between coats, but when I am not getting any funky imperfections I go straight through shooting from primer to base to clear.Crap, have I being doing it wrong?
I started out by dry sanding with 400, then 600, until the surface was dull.
Gave it a wash, then did 1 very thin coat, waited about 2 hours, wet sanded with 1200 again and did another very thin coat.
I let it dry for about 20 hours or so, wet sanded with 1200, until smooth, then did another slightly heavier coat.
This is where I am at the moment, planning on doing another 2 coats, before switching over to clear.
I've had a couple of trouble spots between coats and have had to sand, just make sure to clean the surface very well before you go back to spraying.