I observed lately that lots of people arrived on my blog after searching for "create, don't steal". I realize the stealing of our pictures cannot be 100% prevented, but if you follow some small steps, maybe we can make it a little bit harder for these guys doing nothing but taking advantage of somebody else's work.
Step 1: add a watermark to your photos. I know, sometimes it can ruin the entire photo, but we have to accept this.
Step 2: In photoshop lower the quality of your photo. This is what I've been taught by an internet friend, and I do so ever since.
Again, this will not prevent the theft, but maybe it makes our photos less... attractive.