Im new at this and got some used bikes already pre-rusted. What i do is inspect for rust, sand it off using sandpaper i got at home depot the purpose, then apply first a primer coat then a top paint coat. (both Rustoleum auto paint that comes in spray cans but i spray it into a cup and use a brush.) I destroy the original finish but it had some rust anyway. I figure eventually i can get the frames powdercoated so all i am doing is preserving the frames in the meantime. I havent had any frames off the bikes yet so i havent used Framesaver. Since i am using a bike rack on car and also locking the bikes on streets, they are prone to new scratches so i just continue with my approach,the bikes original finish is already ruined anyway.