Hello
I think that looks rather good! You can improve it by using some of the stuff that's available for the skinners.
JazzOn's tutorial on logo-resizing is quite important to make sure that logos that you place dont turn out stretched (this is due to the way the skin is wrapped around the car body). Have a look in the thread to see how you make the logos turn out better.
Since you'll be spending more than few minutes making a skin - why not do a hi-res version? It'll look much better ingame. So rather than a 1024x1024 skin file, work with 2048x2048 or higher.
You can use the
Master-Skinnerz skin kits to make skinning easier. The downloadable .psd files (can be opened with GIMP too) are layered - so its much easier to "paint" specific parts, add logos and texts.
You can always make skins for S1/S2 cars - you can start to use them when you buy a license (and S2's only £24; and its the best £24 you'll ever spend!).
Looking forward to seeing more skins from you; good luck!
PS: You can use ctrl+s to take screenshots from the CMX viewer (just like in LFS). The screenshots will be saved in the viewer's data/shots folder.