How to make leaf twig, and bark textures for unity trees?

Hello, I am currently trying to make some trees for a project. Making the actual mesh in unity is easy but I am pretty bad with textures. I want to know how you would go about getting textures for things like leaves on trees in unity, or textures for grass. I know I could find some textures that would work, but I want to know how to make them myself. Any advice? Thanks

this tutorial cover creation of low poly tree. both model and texture. you can find more like this in youtube. hope it help…

(you can jump to minute 18 for the photoshop part…)