I don't really do much for texture, I keep it smooth.
However for wear, you could mix the contrast color of your leather color to get a natural grey.
So for example, if you use a red brown, the contrast color would be a blue green.
the wear/or worn look could then be applied in specific areas or thinned down a lot into a glaze, so the "crispness" of color is toned down.
A glaze, if you don't know, is a very thin paint, such that it only tints the main color you are using. the more you apply, the more pronounced the glaze color is becomes. It should be thin enough that the color underneath still shows through.
Follow the link to see how I did my scourges along the same lines as what you are asking for, they are page 2 towards the middle.The Black Halo
Hopefully this will help some.