[Russell Sobie]

For the most part if you are only going to work in 2D and you only plan on making a single skin for a particular car, I would recommend staying away from doing stuff that will require you to span across non-adjacent panels. Getting logos to line up, or having accurate racing lines going down the entire side of the car can be a real pain in the ass if you are not familiar with the mapping for a particular 3d model. Besides... if you are just starting out, you'll probably want to keep things simple anyway. Trying to replicate a real-world livery might put you off the entire process!

What I started with when I was doing 2D only was pick a color scheme I liked (Black/Red/White) and stuck to patterns instead of lines. I collected a few logos and used those on all the cars I did. Maybe do a drawing on the biggest panel in the texture map for some artistic flare.

Another tip would be that you can bring in other existing liveries for the car you are working on and put them on layers above the layers you are working on and set their opacity to 20% or something. Maybe you can "barrow" a particular racing line from one of the other liveries to clue you into where they need to join up on other panels.