Thanks for the compliment martdaman. I got my first Microsizer from my wife for Christmas 2002, and I did my first modding (just painting, initially) in February of 2003. I had been doing 1:48 plastic model airplanes prior to little cars, so I had an airbrush and a bunch of paint and tools.
For me the secret to doing a good job is planning what you want the end result to be, and taking your time getting it done. I can easily spend a month of evenings and weekends on a single car, so I try to have 3 or so going at once so I don't feel compelled to keep working a car while the paint is wet
Also, look at scale model building web sites and forums for tips on painting and finishing.