Do you have a portfolio somewhere?
But yeah basically you could try making lods for props or improving existing ones
You should clone the nightly build (this way you don't have to worry about building the game or lfs etc)
If you do want to learn git to make your own patch, that's fine as well, else if you make something good I or @wowgetoffyourcellphone will commit it for you.
@nifa might have some tips for you on how to get started.