As others have said, KISS (Keep it simple silly) and as interactive as you can...
While more targeted to "classroom" lessons this might be another place to get some ideas...
http://www.astrosociety.org/index.html
Moon, planets, milky way (if visible) and a couple of constellations/asterisms should do the trick...
In the Southern Hemisphere I especially like the Southern Cross...they will have seen it on the flag and it is a good reminder...In the North lands it is the "big dipper" asterism...
Be ready with a few facts:
How far away is that?
How old is that?
How big is that?
How hot/bright is that? etc. etc.
Whenever possible, take them from something the "know" into an extension learning (something new)....
Constellations are always fun because they tell stories...remind them before TV,IPOD, Internet, books etc. people used the stars to tell stories and the shapes helped them remember...
Before it got dark, I handed out a page of starfields that they could draw their "own" constellations on (connect the dots with Ikea pencils) then I gave them the same star field with the traditional constellations/asterisms on them...and then we tried to find a couple of them
Have Fun!