The first time I was asked to write a rubric I had no clue what one was. I was told to research them and write one for a lesson I was planning. Luckily I have to parents who are teachers and were able to guide me through. If you don't have teaching parents here are some websites to help you out.
http://rubistar.4teachers.org/index.php creates rubrics for you, and has specialized art rubrics
http://www.teach-nology.com/web_tools/rubrics/ creates rubrics for you
http://school.discoveryeducation.com/schrockguide/assess.html#rubrics the ultimate rubric site for any teacher-links to external websites about rurics