Here are some materials that will help you at all stages of your teaching career.
OSU Physics TA handbook: Contains information specific to teaching in the OSU Physics Department and some general discussion, too. You will receive a copy of this in your orientation packet.
TA bulletin board: TA communication
OSU Center for Teaching and Learning: Advice about teaching, workshops, programs.
U. Minn. TA program: A well-developed and comprehensive TA training program.
Mazur, Harvard: Peer Instruction information, as well as a number of other education topics, by Eric Mazur, a pioneer of Physics Education Research.
UW Teaching resources
Oregon AAPT: The Oregon chapter of the American Association of Physics Teachers offers opportunities to meet with other physics teachers and share information about the art and science of teaching physics.