Here is a quick, yet powerful tip from Felix Alejandro Hernández Rodríguez. It is simple and all it involves is a couple packs of flour, and can really boost a photo. Here is how Felix describes it:
Here is a simple technique that I “discovered” a while ago… It has been useful in some projects… With this technique you can transfer texture and shadows to any surface…
It’s simple: In PS create two layers. On the top layer place the photo to which you want to transfer the texture and shadow On the bottom layer put the photo with the texture. (in our example the flour). Apply Multiply Blending Mode to the top layer and mask the areas where you don’t want the texture… Simple but effective.
P.S. if you are looking for relevant textures, you can always use a pre-made package like this one.