Recently, I attended a regional conference on programming languages, and I was giving a talk there about my own research. Although it was the first time I gave talk at a public venue, that I am by no means experienced, I had thought of some techniques that I want to share. The most important issue is actually timing, and many of the concerns revolve around that.
The novelty of my ideas really falls in the inverse pyramid organization of slides, but I feel that common-sense presentation techniques should be considered before that for effectiveness, so I would mention the common-sense first.
Pace yourself The amount of time you're given for a talk limits how much material you can cover. After finishing all the slides, you should rehearse at your own leisure. This allows you to determine the natural pace of each slide. You should not rush, and you might even want to slow down a bit.
Remain focused It is likely that you go overtime in the first rehearsal, but the solution is not to speed up; you must decide what to prune. Consider what is the most important message you want to deliver, and only keep the slides which support that message. It is also possible that you may not have enough slides to support your thesis, which is only apparent after rehearsing to someone and hearing back from them in my case.
If you choose to speed up rather than prioritize, you would find that your talk still go overtime and out of focus.
Inverse pyramid scheme After pruning, you might be concerned that you pruned too much, which makes you appear unprepared. The inverse pyramid scheme is a well-known journalist approach that states the bottom-line about a new report first (when, where, what) and continues to the less important facts (why, how). The scheme is devised so an article can be truncated easily by a newspaper editor to fit the page. It can be applied to a technical talks as well.
I organize my slides as a logical tree, but I move the leaf slides to an overflow section. The official talk ends at a slide that says "thank you for your attention," but the overflow slides follow. The idea is that I would not talk about them but refer to them if people ask questions.
My overflow slides contain the hairy technical details that take some time to digest. If you have detailed slides that you don't want to spend too much time on them, they are probably good candidates for overflows. However, if the slides are integral to your talk, then you should just break them up instead.
Conclusion I used these techniques for the talk, and at the end I feel I was well-prepared and well-timed. The inverse pyramid scheme allowed me to employ an "on-demand" approach in showing some slides, and it appeared effective and on-point. However, I think this approach is most effective when used after the common-sense to maintain pace and focus.