Anticipation and anxiety: Everyone is nervous during their first few years of teaching, so do your best to project self-confidence, whether you feel it or not. Ask some excellent teachers to allow you to attend their lectures, so you have some good role models to follow. Throw aside your anxiety and ask one of them to attend your lectures to give you gentle, specific feedback.
While content is probably most important, style is important, too. If something you are doing distracts, confuses or bores students, the content is not well served. Good teaching involves a bit of showmanship and fun for both the students and instructor.