i've done a couple rattlecan jobs, and they're mediocre at best. if thats the way you're gonna go i wouldn't bother stripping the old paint completely, just sand it and rough it up. then degrease the frame good and give it a couple coats of primer. follow it with a few color coats, letting it dry completely and wetsanding on between coats. follow that with a couple coats of clear and you'll have a decent looking job(from 6 feet away).
problem is it'll chip easily and even if you have a magic touch up close is gonna look not so great. by the time you buy all those cans and sandpaper and tape and stuff you'll be halfway to a nice professional powdercoat job. i just had an alu frame powdercoated for 90$ and it came out beautiful. steel frames run under 80$ for a single color including blasting. if it's a bike you care about at all i'd highly suggest that route.