I used to work in a autobody shop so here is the skinny on painting. Like thbirks said you could use a scotch brite pad on the bike provided no rust exists. rust = sand to the metal. If you sand to the metal you will have to primer the area. If you plan to do this all with spray cans, stop right now. In the vegas heat after one sumer the paint will peal and crack. The weather here is just too hot for the paint to last.

I'm actually thinking of repainting my MTB, although I know how to do a professional job, without access to a spray booth and a baking oven, there is no way that I can do it. I found this place on the web, they do bike painting;Class Act Coatings for around $100 (if I read right ) that is really not much at all for a paint job. Paint, primer, clear coat are not cheap and if you did it yourself you would have to pay for extra paint that you probably would not use. Anyhow I would either ask some of the body shops here in town if they would do it, or send it to class act.