Since starting Robust Perception a year ago I've given 20+ tech talks at various meetups and conferences across the world. I'd like to share some tips around the practicalities of speaking that I've learned along the way.
AV, AV, AV
The most important thing is that you can show your slides. Even if there's someone who really wants to talk to me, the very first thing I do when I get to a venue is test out my laptop with the projector and figure out the display settings. I've been more than once caught out by a projector that didn't like my laptop, and the more time you have to organise something else the better. Which brings me to...
Have a backup plan
It's going to happen that your laptop won't work with the projector. Maybe it wants a weird adaptor (you have and always bring both HDMI and VGA adaptors for your laptop, right?). Maybe it's on the blink that day. Maybe it only supports odd resolutions. Maybe it causes all PCs to spontaneously reboot.
Similarly, don't depend on the internet working. In fact assume that it won't work, as even if there is connectivity it is often flaky.
I always have a PDF of my talk sitting on my laptop, and sometimes also on my phone. I try to ensure I can send the PDF over email to someone else's laptop. For big international conferences I go so far as to have a copy waiting in the wings on S3 so that someone else could get it on to their laptop even if all my technology were to fail me.
To avoid the above problems some conferences will request your slides in advance, which will be presented from a central laptop. Make sure you know what software and hardware is being used if you're doing anything fancy (e.g. videos, animations, transitions) and try to do a trial run. If you like to use a clicker, ask if one will be provided.
You should have been given a time slot, keep to it. Have a rough idea of how long your talk will take. For example I know that I tend to take about a minute per slide. For conferences and the like where there's a strict schedule, do a dry run to verify your timing is as expected.
If there's a clock you can see, great. If not, one approach is to have someone in the front row signal to you with their fingers when there's 5 and 10 minutes remaining. You can then give them a nod to acknowledge the message without disrupting proceedings.
Know whether the time slot you've been given includes time for questions, or whether it comes out of your speaking time. Does your slot include time for switching between speakers? It's easy to 5-10 minutes to be abruptly lost from your slot this way.
Lightning talks last 5 minutes. If there are questions, they come out of the 5 minutes.
You need to be considerate of your audience. I'm not going to discuss how your material should be relevant to the audience, that's a given.
When there's questions, will everyone be able to hear the questions? If not, repeat them - particularly if the talk is being recorded. The organiser may ask you to direct questions to a central or roving mic.
Some questions can be long winded, it helps to repeat back the core of what the question is as the audience may not be as familiar with the topic and to confirm you understand the question. If someone has complex questions, lots of followup questions, or is generally derailing things offer to discuss the matter after the talk. Try to spread questions across the audience. If there's only 2-3 people asking questions, encourage other people to ask questions too.
Be aware of the overall timing in context. It's inconsiderate to later speakers to let your talk or questions drag on, or to delay the schedule - even if there's no formal schedule. People are unlikely to stay attentive for more than an hour. If there's multiple talks keep in mind how long the overall event will be, how heavy the material will be across speakers, and what topics other speakers will be covering.
In general keep things moving. I've been at more than one event where the sound system wasn't functioning. I'm lucky enough to have good projection from years of singing, so I will tend to go ahead and give my talk anyway in that situation. There's little worse than/more amusing than watching a swarm of engineers trying and failing to fix an AV system.
Know your style
Know how you like to present, and in which ways you can't present.
I for example tend to use my hands a lot. One thing I've recently learned is that if I have to hold a mic in my hand, I can't hold my clicker in my other hand. Instead I have to keep one hand free, and keep by my laptop to move slides forward. I've never gotten someone else advancing my slides to work cleanly.
If using radio mics or clip-on mics, know how you tend to turn your head. Make sure the mic always picks up your voice, particularly if you've separate mics for the speakers and for the recording. Mics are always hot.
If you like to walk around a lot and the talk is being recorded, know the limits of the frame of the camera. Venues will often have masking tape on the floor marking this - if they don't you can use your bag or jacket.
While it's a bit cliche, don't cower behind the podium. Do not speak in a monotone. Show some enthusiasm. Make yourself memorable (in a good way).
Try to engage with your audience. If their eyes are glassing over, skip the more technical aspects of your talk and switch to more examples. I personally try to get a laugh out of my audience every few minutes to keep them involved.
While I appreciate a nice bit of showmanship, something to be careful with is multi-speaker talks. In terms of skills this is more acting than public speaking. If done well it can be a thing of beauty, however it's easy to come across as forced or corny due to imperfect execution. If not all speakers are of the same skill level, the audience will be left wondering why you didn't just leave the best speaker do the lot. A single handover of the presentation can be okay, but even this interaction should be practised until it is seamless.
There are several speakers that I will go see no matter the topic or what else is on at the same time. Strive to be that speaker.
If you follow the suggestions here organisers and AV techs will love to deal with you. The audience mightn't love you, but at least your content isn't going to be held back by easily solvable problems.
A little forethought goes a long way.