Jeep Willys

I decided to model a Jeep Willys and I am fairly positive that this is almost done in terms of modelling. This is the test render but I want to dirty it up a bit, how would I do this? I have never been good at doing textures anyways, any tuts or tips? Any C&C is also welcomed. Render

Well, it’s a very good start, only make the tires a bit smaller.