I love how much depth textures add to images. And I'm wondering if thats done with brushes (my best guess) or layers (likely combined with brushes). I'd love some insight into where I might start applying brushes and if there are any brushes that are recommended for usual application. I also know that a lot of you create your own brushes. But that also opens up questions about what sort of brushes work best as certain textures. How can you tweak an existing brush to fit a wide variety of textures.

A lot of indeph questioning, but it'd be great to learn more.