Hi guys, thanks very much for all the suggestions. I think the classes are going pretty well so far.
I've just been getting the students to practice basic techniques that I've been learning lately (many of which I still don't even know the full names for), as I haven't had much time to think of anything else to teach them.
My club's style is Shin Shin Toitsu Aikido (Ki Society), so we have more of an emphasis on the Ki side of things. I've been trying to emphasize things in my teaching like blending with uke's Ki and entering when his Ki moves etc etc.
It still is a bit nerve racking being up front teaching when I'm not used to it, but I am starting to find ways to relax and ignore the fact that I'm being watched by everyone in the dojo.
Thanks again for all the great responses, and please keep them coming, as I need some more ideas!