Things I learned/took home from a newbie seminar & camp:

give them a pre-race checklist to take home
give them a training tipsheet (?)

Ask them to give you questions at the beginning of the clinic, then do something else, then answer questions (and some more)
We learned how to fix a flat. May be useless for a sprint, but gives the mind a break.

lay out a transition for them (maybe even let them practice?)

Final maybe useless stuff
Show equipment (regular bike clothes, tri specific)
Put up some bikes as enticers. Perhaps explain about seat angles, aerobars