I've probably done a few dozen or so. To get even what I'd consider a "reasonable" finish, you'll have to spend a few thousand on equipment. Also, you need to be able to create a completely dust and insect free painting environment. One speck of dust will cause a nice pimple on a paint job. One fly or mosquito will always manage to land squarely in the center of a hood and find the strength to crawl about 2 feet across your wet paint before succumbing and becoming part of your finish.
On the dust thing, it's hard to imagine how hard it is to get all dust out. Remember, when you are spraying, you are using compressed air. That will recirculate any dust on anything in your paint area that may be seemingly out of the way. I used to use a garden hose and lightly wet everything in my "spray booth" to make sure that all dust was stuck down before I painted. With the new high quality enamel paint, too much humidity in your spray booth will give you a milky looking finish. I like Sherman Williams for both the base coat and clear coat. With that, as well as with all other such paints, you must get your hardener, fish eye eliminater etc. mixed properly and precisely with each batch in your spray gun.
If you buy a cheap spray gun, you will get a paint job that looks somewhat like a zebra; with stripes in the color. If you paint with too much air pressure, you will get orange peel look. Too little pressure, you get runs. With your painting motions you need to make sure that you don't cross any one area too often or you will get runs or will have the paint too thick and it may crack once dried. If you don't properly wipe off the car with a goot tack cloth before you paint, there is always the possiblity that the paint may not stick any place that someone touched with their fingers. Fingers have oils on them, paint does not stick well to oil. If you don't use the correct primer, and even color of primer, the primer may bleed through after a month or your sand marks will show. This doesn't even mention the fine art (and I do mean that it's an art) of doing quality body work. Even if you are good at the artistic part, if proper procedures are not used you will see your hard work bubble up and fall off later because of rust on the underlying metal. I've seen more 'short cuts' to doing body work than I've seen quality work. It's far easier to take the short cuts that will give you a decent looking end result...for a short while.
Basically, if you want to spend the money for the equipment, I'd still practice on "junk" cars numerous times before I'd attempt to paint something you want to be reasonably presentable. I've seen way too many do it yourself paint jobs that actually decreased the value of the vehicle because of the expense that will be involved to 'undo' what was done.