There will be some prep work..... Use some type of degreaser to clean off any fingerprints/oil/lube residue that may keep the paint from sticking.... You can rough up the stock with some light sanding if you like, but I just degreased mine and painted as usual.
You should get some rubber gloves to wear during the process to keep oils from your hands from getting back on the metal parts after you degrease them.
You can use primer is you feel the need.... I have heard wiping the metal down with distilled vinegar will also help the paint stick better.... kind of etches the metal, but I've only done that on a boat.
Mask off any mating parts or parts that slide into another (like the barrel into the action or the rails on the action slide)..... and the mag tube.... otherwise over time the paint may scuff off and create an issue with things working properly on the inside.
I finish mine off with a few coats of the matte clear coat to help the paint last longer.... It is paint and if handled rough, will chip off regardless.... But touchup is as easy as spraying a spot on a paperplate and then dabbing the paint to the chipped area with a q-tip or small paintbrush.