Holley's got good advice. Here's some more (perhaps not as good, but it is free...)
- Acrylic paints (water based) are much better than they used to be. Check out the Tamiya line and you won't be unhappy. There are tons of awesome automotive colors that look great.
- priming isn't 'mandatory', but it is a good thing. It basically creates a nice uniform surface for the paint to stick too. If you don't prime, be sure that you wash the model as Holley recommended.
- get used to the fact that the paint will take a while to dry (especially with enamels). I generally paint the body of a kit first, and then work on the other bits and pieces while the body dries. I usually wait at least a week for the paint to fully cure. If you do this, you won't get fingerprints in the finish!!
- as for that C5R, you might be able to save it. There are ways to strip paint from a model, but they're all require care and caution. If you're a 'younger' builder, then an adult may be able to help you with that.
Good luck on the Viper and hopefully you'll be able to get some pictures and post them here for all of us to enjoy!!
Have fun !!!!
Murray