Layer Masking is a technique you can use to help build textures into your images. Gor example you could create an old film poster and by using this method you can make it look like like it is worn, torn and ripped by using layer masks. You do this by dragging in a texture that suits the style of the work you wish to achieve and play around with the settings in the layer mask menu, then it eats away the image of where the texture is placed on top off to leave you with rips, tears and texture.
This was my influence.
After adding textures from external imagery, I could make it start to look more reaistic.
I definately want to expand on this technique and will hopefully be shown how to.