remove old paint with paint stripper then sand down with 500-600,then degrease and a light dusting of etch primer,2 or 3 coats of high build primer wet flat with 800 -1000 wet and dry,degrease again then spray 1 light coat and finish with a couple of wet coats
is that some kind of old pre war type finish, fasinating
no seriously, good luck with it,
it's all in the prep, so one tip, dont worry how the primer looks, if the frames pited or small dings, flood it on then
flat it off following the shape of the tubes, it will come out perfect