I follow a fairly simple policy on the usage of my images.
If you want to use any of my images, get in contact with me, and we can chat about it. (And no, I do not work for exposure, money is usually involved)
If you take an image without permission and use it any any form, you will receive and invoice for payment. This will be for a high price. Negotiation is only available if you contact me before you use the image.
Seems simple to me.