I learned as President of a large radio club re presentation:
-Keep it brief.
-Hands-on, interactive, is way better.
-Great presentations do something unusual that most haven't seen or done but might want to.
I used to give a lot of the presentations myself (maybe half of them, the other half were "guest" presenters who were either club members or not) and the top one in the hit parade was setting up a 70cm moonbounce station (working) in the parking lot outside the meeting. I had it all set up a couple of hours in advance, and about 30 mins into the meeting time the moon was in a good position. Ran a kilowatt to four stacked 21L beams from a van-mounted station, and very first key closure yielded an echo everyone could hear. People were amazed.
One of the best "guest" presentation which also rocked the house was when Ulrich Rohde DJ2LR (now N1UL) brought in a homebrew receiver which he built in his lab and demonstrated it alongside a few modern (then) Japanese transceivers, using a 40m dipole we stretched across the room (indoors!). Unbelievable. His "talk" lasted only 10-15 minutes but the live demonstration went on for as long as people wanted to play with the equipment. Very, very impressive.
This thread was very useful as I was preparing a presentation and a demo at Wellesley Ham Club last week.
I created only few simple slides ( http://ag1le.blogspot.com/2012/01/wellesley-ham-club-presentation.html
) and focused on demonstrating the audience how to use PowerSDR and connecting it with various other free software applications, such as Ham Radio Deluxe, Fldigi, JT65HF, Spectrum Lab, WSPR, PolarPlot etc. We also built a HF station in the venue by pulling some 200+ ft coax through windows to a mobile antenna mounted on my car outside.
I agree that live demonstration is more effective way to keep the audience engaged. It takes a bit more effort and preparation but it pays off.
73 Mauri, AG1LE