ask how they are stripping it and go for the most gentle method (preferably some sort of chemical or a very gentle abrasive). Might want to fit plugs into any important areas – head set, bb threads, seat post etc as they could get damaged by an abrasive.
Take any stickers off and tell them it’s a steel frame. Sometime stickers don’t fully come off leaving the paint underneath which is surprising considering the nasty chemicals they use. I would get it chemicaly stripped rather than media blasted. It’s much kinder to the material.