So, uhm, if you don't mind, what are these textures and how do you use them? Do you import the picture as a brush, do you lay transparent color over it, or is it something to do with the clone tool?
The textures are just normal pictures. I draw the picture first. Then I open the textures as layers and set that layer to whatever looks the best; overlay, multiply, screen, soft light, etc. If I like how it looks, I use the lasso tool to select the area I want that texture applied to and delete the excess. It can be pretty tedious, but I think it's worth it.