Whenever you purchase a resin body or other parts for your model building, always try to find out what type of resin is used to make the item. That has a great bearing on what you use to clean or work with the piece. A good example would be Big Donkey Resins. Larry produces some terrific stuff for us modelers and let's say you purchased a body from Big Donkey and then as you do with your styrene kits, you give the new resin body a good soap and water scrubbing. Big No-No!! NEVER use any water or soap on Big Donkey Resin. Larry, like many, uses a Polyurethane Resin and water might/can re-activate the resin, giving you some areas that will be sticky, tacky and "gooey" and that will NEVER harden again.
Lacquer thinner, acetone, or alcohol will not harm the resin piece as long as you don't soak it in it. Just wipe your new parts, sand, wipe again and prime. I use Tamiya grey primer. I have tried a half dozen other primers and found that it works best for me.