More of a pain in the *** than something that is hard to do. It's kinda like cutting the yard, it isn't difficult, just tedious, boring, & not attractive to most of us.
I started with a cheap car, and just started cutting. I fuct a lot of stuff up, but I fixed it later. I'm in the middle of fixing my first ever fiberglass creation (and man is it a mess) that I made like 4 years ago. It will look tits when I'm done though, just from what I've learned by reading tutorials and getting my hands dirty.