I read the wiki pages, and I know what I'm looking for in terms of how it's supposed to look when it's finished. However, I don't have any idea what I'm doing when it comes to unwrapping the diffuse and skin UVs. The following questions are intended for experienced mod vehicle creators (and perhaps also the devs if they're not too busy): How do you deal with the two UVs, and which one do you do first? Also, what should I pay attention to in the process? Here's what I have at the moment. Despite the label, I haven't quite decided which UV this is gonna be yet, but I'll sort it out when the time comes.
Not a vehicle creator but I can give you a few tips, I'd recommend packing you're uvs and possibly getting a plugin to help better manage them. Unless you want to move onto blender 2.8 which while I use for almost everything now is prone to crashing and weird issues does make uv mapping a lot easier. Just make sure to use as much uv space as possible to allow for the highest possible texture quality on the parts that need it.