Wet sand the frame with fine grit sandpaper and CLEAN the frame well with alcohol after.  don't paint any bearing surfaces. Use painter's tape and/or rubber cement to cover anything you don't want painted (rubber cement peels right off after). Take your time when painting and don't rush. Give the paint several days to cure before reassembly. I built up a DengFu M06 and just rattle can painted it - Gloss black rear, Red Front (see pic) and it turned out great. Just take your ti.me and be meticulous