For FL Users, here's a real good tutorial on using the FL Scratcher to add scratches to your production work. Some things on this vid aren't set in stone but it's a great starting point. After you get the hang of it, you will discover other techniques than will enhance your work even better. At first glance it looks kinda complicated but after a few tries/tests, you'll pick it up very easily.
This guy uses a very common sample but you can use just about anything you want and get great results. Check it out...
This guy uses a very common sample but you can use just about anything you want and get great results. Check it out...