Hmm texturing tutorials... thats more like art tutorials with photoshop. I suggest looking up how to do "art" over a sketch. Its a progress when you take a drawing you made and then use lots of different colors and paint brushes to paint overtop of the drawing and make it a actual painting in a way. Some people are absolutely amazing at it. I dont know any sites that give these tutorials off my head, but i have came across tons in the past. I think it may be called matte painting.. not sure. If you learned this, then you could do the same technique for your models textures.