Hey Leon,
I'm still a rookie in the matter,
but there are a couple of different approaches to repainting.
The primary factor is the programs you use.
If you google a bit for it, you'll find lots and lots of sites with hints, tips, tactics and even some entire tutorials.
Most of them are made for FS9, but it's (except for bump and normal mapping, which I haven't figured quite out myself) reasonably similar for FSX.
I had links to some very good, very clear sites, but unfortunately my laptop crashed a few weeks ago, so I lost them...
I kind of took the 'head first' approach, I started repainting first, and only then started to look for how-to's
I'm sorry I can't be more of a help at the moment.
Good luck with it!! I hope to see some repaints from you soon!!
Tyrion