I found this on Flickr. It was posted by Texture Tutorial on Flickr - Photo Sharing!. Im gonna try it in a little while and post a few.

Thought I would share:

I use windows and Photoshop CS3

-open your image in Photoshop
-do all your editing now
-open texture you want to apply
-Go to window > arrange > cascade
-select your move tool from your tool box on the left
-drag your texture onto your image
-go to edit > free transform (or Ctrl T) and resize the texture to fit your image.
-go to your layers palette and select your blending mode. I mostly use soft light or overlay. Every once-in-awhile multiply or screen. It depends on your taste and photo.
-in the layers palette adjust the opacity to your taste. Ignore the face/skin because we will fix that using the layer mask.
-click on the check mark above the layers palette once your blending mode has been applied and your happy with it.
-to remove any unwanted texture from your image click on the layer mask button at the bottom of the layers palette.
-the layer mask will be white. Make sure the two boxes in your tool box are black and white. Black on top. You always want the opposite color of what is in your layers palette.
-select a soft round brush (from your tool box). I start with size 300. Set opacity (in your tool bar not layers palette) to 30%. Erase texture from skin. You may have to change opacity to your liking. If you make a mistake click on the white box ( in the tool box) and go over the image where you goofed. Change back to black.
-when finished and happy with your results go to Layer > flatten.

__________________