What is the proper way to paint a bicycle? I started a while back restoring a custom-built tandem bicycle, and I sanded it down to bare metal and just used spray paint (Rustoleum I think, took the bike completely apart to just paint the frame) to give it 5 or so coats, then a clear coat... but the paint still comes off pretty easy. To paint it up I just hung it up by the back forks and did light coats. Anyways, it looked good in the end, but the paint still comes off pretty easily.

What are the steps that someone should take to fully paint a bicycle that already has a coat of paint on it, that is tough and good looking?
If you're going to use paint, I have had some success with the following:


Bead-blast (or sandblast) the old-paint completely off the frame. Sandpaper just isn't as good. You can rent a bead-blaster.
Clean thoroughly with ethanol and rags. A white rag should stay clean if you rub it on the frame by the time you're done.
Prepare a clean environment for painting. Get a roll of plastic tarp and literally make "a tent" in which you hang your bike. Cut slots in the wall so you can stick your hand in and apply the paint.
Apply the appropriate primer coat (critical for success)
Apply layers of the spray-paint color (this is where experience makes a difference, I tried really hard to get it uniform but only pros can really get it right).
Apply clear coat. 


As an alternative to paint, you can have your bike professionally powder-coated. This will give really beautiful results. I have had this done, but had problems with a lugged frame. After a few years, I can see that the powder coat has started to admit rust in the edges of the lugs. It is probably better to reserve powder coat for fillet-brazed (tig-welded) bikes. I am not sure if there are special preparations needed to powder-coat lugged frames.