just a remark...
I'm not a professional, but made some discoveries by trial and error...

Prepairing the surface, before even getting to the spraying, that's just as important as everything else!
I used several layers of filler and sanded them down again until the surface was mirror-like... several days can go into sanding and layer after layer of filler or basis can go by before the actual paint comes into play...

Keep calm, take your time when sanding; one hour more into the prepwork and you avoid disappointment afterwords!
If you prepair your surface with confidence and with no hurry, you can get good results even with a spraycan (eh, on minor surfaces or for a patchjob)

probably stating the obvious, but hey, we're posting advice for starters, right?

there's nothing like the look on the faces of your friends, when you tell them you've done it yourself, outside in the backyard...

just a thought here...
hope it helps,
greetz,
tom