How can an artist protect his work from copies?

Watermarking isn’t very pretty, but its sadly one of the best ways to protect it from copying.

upon creation, your work is automatically protected from copying. you get a copyright in your art as soon as you make it, which prevents others from reproducing it etc.

Have such a uniquely definitive style that any rip-off would be immediately apparent ;0

Benjamin is correct, works are copyrighted on publication. You can also tag them with a copyright and other info in Photoshop. Watermarks don’t do much besides making the image ugly.

Also post a Creative Commons license on your site.

Well the sad reality is even with a license people will steal your work. The internet is so big that it can become practically important to figure out who stole your work. For example, a group of underground design thiefs are distributing my own custom design for my website to other people. The most I can do is send them a threating email. If they dont take off my work, the only option I have left is ridicule them on my blog.

So I am going to say, go for the watermark if you want credit for your work

Even with the copyright, when displayed people who are viewing the image wont really notice it, and ignore it entirely. And even if they do look at it, they’re most likely to not know whether or not it’s stolen. Watermarks are ugly and obstructing, so I would just suggest a combination of the two. First take the legal approach and put the copyright in an un-obstructive area that doesn’t clash poorly with the composition. Then Incorporate your website name, or any watermark design you would have come up with, into the actual picture itself. Rather then just some blunt ugly thing slapped on carelessly, you have one whole piece of what we all hope is beautiful artwork. Pixelgirlpresents.com has an excellent supply of artists who do this.