I watermark all my photos. I think it takes away from them visually, at least a little bit, but it adds a little bit of friction to unattributed copying. Sure, it's trivial to remove the watermark, but it means someone has to think "yeah, I'm going to be that guy and intentionally remove someone's name from their work."
I don't repost or even "favorite" images without attribution. And when I find people using my work without attribution, they get a very nasty nastygram.
Hey, while we're on the topic, do you ever wonder where those "hamsters every hour" accounts get their images (which never have attribution)? Yeah, they're scrapers. I block them. Don't follow them.