Just use auto paint.
Prime, bass coat and lacquer.
1. To get a top quality finish, use 1200 grade wet and dry paper to take all the shine off of the body first. keep the paper wet and use some soap with it.
2. Either use pre paint cleaner or some washing up liquid and plenty of water to get all the residue muck off. Then dry thoroughly and leave it in a place which is hot. Airing cupboard / next to a radiator. This will ensure the primer will bond well to the plastic.
3. Prime and wet flat with 1200 grade. When you wet flat you only need to take off the rough surface, not right through the primer. Allow the paper to become creamy but don't let it dry out. the flatted surface should be perfectly smooth and have a sheen finish.
I always use etch primer. Upol is good. (Never spray thick coats... Ever). 1 dust coat, 30 minutes then wet flat and leave for an hour. 2nd coat, 30 minutes then wet flat and leave for an hour. 3rd coat. No wet flatting, let the paint fully dry. The longer the better, over night is good.
4. Wet flat the primer and clean the body thoroughly. Leave to completely dry in a warm place.
5. Now you're ready to add the bass coat. Again, you want a light dusting and allow it to dry before the next coat. No need to wet flat just yet. Spray another coat, you should have the body covered in the color now. Wet flat then Leave it for 30 minutes and spray another coat. No wet flatting after this. Another 30 minutes give it a light dust coat.
This final dust coat gives the lacquer something to bond to. Spray the lacquer very finely, keeping the spray can on the move, spraying past the model and back again. You don't want any area getting too much on it.
It should all begin to look orange peel textured, stop there and leave it an hour. Don't get any dust on it, the paint will stay tacky for quite a while.
Nearly done....
Final coat of lacquer. This one is the most important. Again you want to spray finely, spraying past the body and back again. But this time you need to keep going until a glassy gloss finish. Once you see this finish, don't spray anymore over it, there's a risk of it running which will screw up everything.
While you're spraying you see any part of the body which doesn't get that glassy look, slow down the movement on that part to get the lacquer completely uniform.
It's a good idea to walk around the model as you are spraying. You are better off moving rather than having to move the model.
Now it's done. Leave it somewhere warm over night. Even the next day the paint won't be hard, you'll easily be able to mark it with a finger print if you press hard. Be careful.
Personally I would just leave it alone for a few days in the warm.
Then give it a really good polish to buff up the shine, still don't go too hard with it, the paint will need a few weeks to completely harden.
Hope that helps. "thumbsup"