for a steel bike: Chemical remover. for a good paint job you need to get all the paint off no grinders, etc

Rattlecan jobs can come out very nicely, but are in no way as durable as automotive paint

steps at a very high level for a steel frame

remove all paint

acid etch primer

sandable primer

sand smooth

multiple thin coats of color, pay careful attention to recoat time...... IMHO easier to plan for a day and recoat as soon as possible

multiple coats of clear