If you saw my work from 20 years ago, you'd be inspired - thinking - man - that dude did THAT - and now he does THIS?
We all start somewhere. Study, study and study more. Sponge up as much good info as you can. Be a student of the craft, and that at some point, you'll be a master of craft. (I am no where near that level - but it is something I continue to work towards).
As far as software - I use Photoshop with a white truck as the base, bring in my vector based image out of Illy or Freehand and then put on its own layer, then choose multiple for the layer style. Once in a while you need to tweak some other things but usually its pretty realistic.