Hey Dave, glad you're having fun with the Barrage. Don't be afraid to paint, in fact, when you do your first one, you'll want to buy an extra body or two, just so you can try different tricks. In the "Paint and Body" section of RCC, I've posted a few times answering questions for other beginner painters.
On lexan bodies, which most kits come with, unless you specifically buy a "hardbody", like from Tamiya or RC4WD. Lexan bodies come clear, hardbodies are usually white, like a Monogram or Revell model kit, made out of polystyrene.
Painting on the inside:
Before you paint, you'll want to wash the inside of the body with a mild detergent like Dawn. Get in all the corners and recesses. What you're doing is washing off the mold release agent. If you try to paint without washing, the paint won't stick, then let dry thoroughly. I usually let a lexan body dry overnight. You can wipe it dry with a rag or paper towel, but you're sure to miss some moisture. The outside of the body should have a clear film over it, that you'll peel off after you paint the inside. There's usually a sticker on the outside of the body, usually the front windshield, that says to remove the clear film after painting. Painting on the inside means your paint won't get scratched rubbing on rocks and obstacles. I'll talk about painting on the outside later.
When you're ready to paint, you'll need to use a polycarbonate paint, like a Tamiya PS paint. Tamiya paints are a little pricy, usually around $6 for a small spray can, but well worth the $$ knowing you're using the right paint. Watch when you purchase, because Tamiya also makes a TS paint, which is for hardbodies. You can also use a Rustoleum or Krylon paint-for-plastics, but my advice is that you use at least a Clear Tamiya PS paint against the lexan before using another brand, then the color of your choice. The PS specific paint when dry, flexes, preventing flaking. Also, before you paint on the inside, most clear bodies come with window blanks that you have to position over the windows so they don't turn out the same color as your body. This is important if you're going to make an interior with a driver that can be seen through the window. I use them just so the windows aren't the body color, but then I remove them and back the finished color and windows with black, like tinting.
Painting on the outside:
My Crawlers are painted on the outside, and this is my method for camo, you can do as you like. I'll paint the inside first with Tamiya PS-14 Copper, backed with Black. First coat on the outside is Tamiya PS-12 Silver, followed by Krylon Paint-for-Plastic Chalkboard Green, Testor's Flat Black, Flat Red, and Flat Brown. The idea for painting on both sides, is that as the outer paint gets scraped off, it exposes the silver as bare metal, then if that scrapes off, the copper as rust......I've yet to see that happen, lol.
Just remember that when painting multiple coats, especially when using different paints, is to let each color dry thoroughly between coats. Another important item to remember, is you can use Enamels over polycarbonate paint. Polycarbonate paint is an Acrylic, thus it flexes when dry. Do Not use a lacquer based paint. The chemical composition of a lacquer based paint will re-activate the chemicals in an enamel or an acrylic, even when dry, and ruin your paint job. I speak from experience. Rustoleum, Krylon, & Testor's model paint are all enamels, they work well with the Tamiya PS paint, as long as you remember to let the Tamiya cure thoroughly, usually 12 hours, your time may vary depending on humidity and temperature.
The only time I painted without letting the paint dry between coats, was when I painted one of my SCT's, and I wanted the paint to blend. Turned out cool. Went from white, to yellow to orange to red.