Just do it. The nice thing about a $15.00 Murray is you can't lose much by screwing it up. Even then, you'll have learned something so it will never be a complete waste.

I've rattle can painted a bunch of bikes. The only time I got satisfactory results has been when I first used a chemical paint stripper to remove ALL the old paint. That might involve more work and money than you're willing to invest in a $15.00 Murray.