Touch up
Give your bike a clean and inspect the frame for any scratches or damage.
Minor clear coat scratches can be buffed out.
Small paint scratches can be sanded down, filled in, and fresh clear coat applied.
Remove rust and re-paint to protect from further damage.
Flaking paint around edges, braze-ons, and dropouts can be sanded and re-painted.
Dents
Dents can be remove from a steel frame. However, the process usually will damage the paint.
Repainting
Sand down the paint to the bare metal and customize the paint job.
Mask off areas for separate colors, or create text stickers for a cool effect.
You can find bike spray paints to do it yourself or take it to a shop.
Decals
Use a heat gun to remove damaged decals.
Find replacement decals for many vintage bikes on ebay.