I've painted quite a few cars, mostly with good results. Paint is not permanent, if you make a mistake it can be fixed. There are also lots of good books on the subject. Painting is kind of an art though, you either have a knack, and a feel for it, or you don't. For me the body work is hard, but spraying paint is easy. Can you paint well with spray cans? If the answer is no, don't waste your time and money. It's really more about your natural feel for it than whether the paint is in a can, spray gun, or even on a brush. If you think you may have natural ability, learn on smaller objects than a car. There are many things to consider when painting a car, temperature, humidity, the envirionment you will be painting in, type and brand of paint, temp. range of the reducer you will be using, additives for the paint, all of these need to be matched, and be the same brand. Will I need a hardener? Do I need a fish-eye remover? Viscosity of the paint, etc.
I could go on for a long time, and the list could get pretty long. Keep in mind though that if you want to do this that you can. I have no formal training, I learned it all on my own, with a little help from my friends. All things are possible, just depends on how determined you are.