Edit: added headings!

STYLE

> [slides] are not cue cards for the speaker

Personally I disagree with this point and have developed a presentation style I'm happy with based on the slides being my cue cards (average 5-10 presentations / year for the last 15 years).

I do NOT read the talk from my slides and can't stand it when speakers do that! But, each slide should jog my memory of everything I need to say at that point. Maybe I'm talking about some stats as background, fine, the slide should be a bar chart of those stats, or a map, or an illustrative photo. Rarely a list of bullet points, though I don't prohibit them altogether and will tend to conclude with a list of bullets to leave in the background as a summary while I take questions. Overall the slides should complement the talk, not be a duplicate. But they serve a second function of reminding me of all the things I need to say.

As a programmer you will appreciate the reason for this: I have cut the number of entities I have to process in my head from three (slides, audience, notes) to two (slides, audience). Keeping track of and having rapport with the audience is essential to me, even if that just means looking at people to see how engaged they are. With notes/memory in the equation I used to get a lot more nervous and not pay enough attention to the audience. Cutting out the notes allows me to focus on communicating better. It's a shared context, the audience can see exactly[1] what I can see.

If you're in sales then I see another tactic used instead, which is to memorize the talk so thoroughly that you don't need notes or presenter view. Fair enough. I'm an academic researcher; while they say all our presentations are a sales pitch on some level or other they clearly aren't expected to be as slick as "sales" sales. My constraints are having limited time to prepare, and wanting to stay natural. I do rehearse but I don't over-rehearse as I find that kills my own interest in the talk as well as taking more time. Usually the minimum for me is two full run throughs, probably stopping the clock multiple times during each to apply edits as I see fit (hopefully only a few edits second time).

HANDLING CONTEXT SWITCHES

The one exception to [1] is context switches. As others have said, finding the perfect words for the introduction to each new topic really helps get the flow going. These can be remembered, written on notes, written on slides, written on slide notes visible in presenter view, whatever.

I'm a big fan of presenter view, not for notes, but purely for the ability to see the next slide and introduce it slightly before the change. It helps to leave each slide knowing what direction you're going in so you're not surprised by the next one. I do worry slightly that I'm dependent on presenter view and turn up early at each venue to make sure I can get it working (not all of them can).

NERVES

Someone said don't drink too much alcohol. Based on my experience as a performing musician this is true :) Same goes for caffeine for the opposite reason, it really heightens the nerves. On the subject of nerves, just accept that some talks seem to go better than others. If you find yourself having a failure of confidence, take a deep breath and keep going. Easier said than done I know, but it always feels worse on the inside than it really looks; I have had people come up to me after talks where I thought I did awfully and tell me how engaging they found it.

AUDIENCE ENGAGEMENT

If you can find a way to further engage the audience without forcing it - quiz questions, polls etc - go for it. Quiz questions can help set context for a new topic. Despite my love of the material I've never really been a lover of talks and can get pretty bored in the audience, so I really appreciate this sort of thing.

Example: on a few of my talks lately I've showed a picture of some protestors up trees by a road, asking who can name the incident. (Protests vs Newbury bypass construction). Followed by more protestors and an airstrip (former US nuclear base Greenham Common). Most of my UK audiences will get these right. Finally I asked what links these two things. They may or may not get the latter: the success of commercial development on Greenham Common, when it ceased to operate as an airbase, was blamed for the failure of transport models to correctly predict the effect of Newbury bypass. Doesn't matter whether anyone guessed the final answer, which is obviously a bit specialist. The point is I've now got people thinking about the many interconnected elements of simulating transport which is a great intro to the topic.