There's a fair amount of resources about painting models available with a simple Google search. If you want something more specific to TF's, the tfw2005.com boards (the Radicons section specifically) have some great tutorials that will get you started.
Paints are available at any good hobby shop (possibly even a few ordinary ones) - unless you want to get into some serious repainting involving airbrushes and what-not, I'd suggest water based paints as they're less fuss. Citadel and Tamiya paints are what i use.
Washing is often a good idea before hand, it removes any dust and plastic lubricants around the joints, etc before applying the paint.
Best suggestion I could give to you is practice some techniques on a less valuable TF first (preferably a junker) so you can get the hang of using brushes, the consistency of the paint, how much to apply, etc, before moving on to something more important to you. If you're anything like me, you'll skip this advice entirely and dive in head first...

Go for it dude! And post up the results in Grapple's section here, OK?
