I don't know much about prepping the car although it would be good if someone who does would give us all a bit of detail, but I have painted two of my cars.
All I can say is, practice on something else first. My first car had about 15 runs mainly along the crease that goes the length of the car (not a skyline) and the second car I did had about 5 smaller runs.
It's harder than it looks, but I think if I was more patient it wouldn't have been such a problem.