mississippivol
You can use automotive paint; but you have to be very careful to prime the body properly with a quality automotive primer, or the paint will eat the plastic. You should experiment with a junk car body that you won't mind messing up in order to get a feel for it. The thickness of the paint won't be a problem.
I'm having a slight problem understanding this comment. The thinner used, for the Primer, is the same that is used for the paint. The plastic is made with Petroleum products and so is the paint and primer. Should I expect my two corvette's that I painted three year's ago to melt, eventually? The fiberglass after all is another mixture of plastic resin's with Petroleum products. I think a lot of people are confusing solvent based paints, with the old Floquil paint that would attack the plastic slightly, if brushed on, not sprayed on. One of my Grandson's, for the past year, continues, to play with a Tamiya 1/14 scale RC truck, that I painted with nothing but Automotive paint. Silver base coat and Metallic Blue over it. If you give it a couple of dust coats first, you won't have any problem's. As the OP mentioned, he is new and probably does not have an air brush, which would be ideal. So he should practice on some scrap, with a rattle can spray, for they do put out more paint, for model painting.
zstripe