I'm 61 and still learning. Thank God I still can.
Since I lost all my filters for PSP and took a long hiatus as to computer art prior to joining SimV, I'm still kinda rusty and not a very good teacher. But, if you don't have filters to create certain looks, like orange peel, you can do some things manually. It just takes time and effort. As to wear marks and/or weathering, I try to 'spray' a little smoke color with opacity and density set low, then smudge it when I want an exhaust look. Sometimes works for minor oil leaks too. Just try to imagine what the real thing would look like and how you can use your tools to recreate it. For wear marks, try the lighten setting on the retouch brush, set as low as possible that will still give some noticible change with a few strokes. It helps if you have a pressure sensitive drawing tablet and set it to vary opacity and width, and color as well, if you are using the paint brush. That is pretty much all this feeble old brain can think of right now. Hope it helps.
Cheers
Larry 

Based on what I've seen Jake, you have the skills, you just need a little practice. And you are welcome. I would not know a third of what I know if a lot of different people had not helped me along the way. It is an honor for me when I have knowledge to pass on that helps someone else. 
As to the 'contest', it's worth a try. But don't give up on yourself doing it either. 

I certainly hope not.