I just finished doing a pink bike (for my girlfriend, not that i wouldn't ride one...) using ace hardware brand grey primer, pink spray paint, painters touch english rose accents on the lugs, and automotive quality clearcoat, and it's beautiful.
The important steps (as far as I see them) are:
1. Sand: this doesn't have to mean striping the frame, just creating a rough surface for bonding
2. Clean: paint doesn't like to stick to a dirty or oily frame, I used citrus-based surface cleaner followed by a rinse of the frame.
3. Prime
4. Paint: pay attention to the can directions, and don't try to do one thick coat or anything. also, give it sufficient time between coats.
5. Clearcoat: buying a good quality (i.e. automotive) clearcoat IS worth the extra money if you care about the paint job looking decent and not flaking off right away. The one I picked up at the local autobody shop was called "U-POL Clear #1" I think, which was $18 a can. Needless to say, this does not compare to a multi-part clearcoat that must be sprayed from a pressurized gun, but the guy at the shop said it was the best aerosol one that you can get.
6. PATIENCE!: I can't emphasize this enough, after you have finished the paint job wait AT LEAST 48 hrs before handling the bike or trying to install components. The paint might say that it dries much quicker than this, but it takes time to harden completely, possibly longer if it is humid or cold where you are.
Hope this helps!