Websites with tips on overcoming nervousness and other good advice for new teachers:
http://trc.ucdavis.edu/trc/teachguide/individual.htm
http://www.teachingenglish.org.uk/talk/questions/nervous_teacher.shtml
http://tep.uoregon.edu/resources/faqs/presenting/stagefright.html
http://www.ls.wisc.edu/TAtips.htm
http://www.columbia.edu/cu/tat/manual/7_performance/firstday.html