'Rattle-can' paint jobs are hard to pull off well.

Powdercoating isn't super expensive for something like a bike frame, and is the most durable type of paint you could put on the bike. Just pick a color, and they put on a nearly indestructable coating of colored polyester on your bike. No nonsense, and good protection for the frame.

Cheap sprayguns can sometimes work out well for bikes because they suck on flat surfaces (which is why they are cheap) but do nicely for tubing. Automotive paint is tricky to work with though.

peace,
sam