The best way to protect it, as counter-intuitive as it may sound, is to publish it on the web.  Make sure your name is on it. 

By getting visibility for your work, your name will be associated with it, getting protected by more visibility rather than less.  Self-written terms of use can govern re-use of materials ("fair use"), but I would suggest looking at creativecommons.org where they've done significant work in this domain.