Wax and grease remover all the way. Blast all crevices real good with portable air or vacuum it completely. If you don't get all the dust out of the nooks and crannies, it may come back to haunt you when you shoot it, as it will blow back out onto your fresh shiny coat.
You haven't told us how you intend to paint it... airless? roller?
Careful how you ventilate. Depending on what the volatiles are, you may be blowing yourself up! If in doubt, better to positively ventilate with some furnace filters taped onto box fans to keep out large dust balls/insects (and isolates to an extent the fumes from the electric motor), blow fresh air into the makeshift paint booth with screens inwards and a vent hole opposite with furnace filters venting out too. That way you don't draw volatiles through any electrical arcs which may ignite flammable fumes.
Lastly, you may consider renting a paint booth altogether. Your results will be much better (visibility from over spray is greatly reduced!) less crap in the air, dry shop air... good lighting. etc. The many toxic chemicals in modern polyurethanes are meant to be used with expensive fresh air respirators, not the $40 Home Depot air purification kind. The health hazard is cumulative. That is, after a couple exposures many years ago, not much solvent makes me itch and break out and get dizzy now a days. (I know when you're young you don't think about stuff like that). I knew a auto body pro who had to find another profession because it was killing him, he was only 26 or so. Oh and most those vapors are transdermal too --You soak it up through your skin.
Ok big brother rant over.
Given the choice, painting by roller sounds very intriguing.