I have always allowed free access to all my images and licensed under a Attribution-NonCommercial-ShareAlike Creative Commons license. However, I discovered that several people have been using my images for commercial purposes. I found this out through the "Google alerts" service. Not that I really mind the pics being used for commercial purposes but I would have appreciated it if they had attributed the pics to me or at least asked me for my permission before using them. Some companies did ask me for permission but a lot of people didn't.
In the end I decided to put "All rights reserved ©" on all my photographs. Now, only I can print photos and only friends and/or family can download them from my account. If anyone else is interested in using my pictures for any commercial purposes, I would have to charge them for it.
BTW, this happens to be the most popular photograph in my account:
A picture of my sister's hands covered with henna before her wedding.