This simple tip is something I've been doing for a couple of years now, and it's saved me a lot of time and frustration. After we get photos back from a studio, I print a set of clear address labels with the subjects' names, ages, and date of the photo. Then, as I cut the pictures apart, I put a label on the back of each one. I haven't had any trouble with the clear labels staying stuck on, even after a couple of years. No more worries about forgetting to mark them, or pens that bleed or smear. Quick and easy, it definitely works for me!