How do you give a great online presentation?
Rehearse. Online. A lot.
Rehearsals are where you make your money.
Step #3, below, is the most important one.
Both in-person and online presentations require the same amount of rehearsing. When presenting in person, you'll want to rehearse in the actual venue. The same applies online... Rehearse in the medium you'll use for your live presentation.
I recently gave a presentation that lasted less than 20 minutes but I spent several hours practicing it, over and over, so it would flow smoothly. Rehearsing/practicing/simulating is how we make hard things look easy.
1. Use big fonts.
When online, use no font smaller than 50 point since some people may be watching your presentation on a mobile device. Ideally, use a much larger font than 50 point.
In my presentation, the smallest font I used was 56 point on one slide with nearly all of my other slides using a 72 point font. The only exceptions should be references at the bottom of a slide such as, "Source: United Nations Charter" or text used for effect, not to convey specific information.
2. Prepare software to be demoed ahead of time by scaling up fonts.
This applies to Web browsers, apps, command line, etc. Keep in mind that your full-screen presentation will be scaled down on other devices, i.e. most people do not view YouTube videos at full screen.
3. Practice your slide deck many times, online, while recording it.
I use Google Meet for my presentations. To practice online I set up a Google Meet for myself and I attend the Meet on another device, simultaneously (one device for presenting and the other device for viewing to simulate an attendee). This gives me an idea of how my presentation will look to others; plus it'll gives me an idea if my ISP bandwidth is adequate since I have two simultaneous video streams. Ideally, when presenting, make sure no one else on your network is "stealing" your bandwidth by steaming videos (YouTube, Netflix, TikToc, etc).
4. Don't cut it close, time-wise.
Plan for delays during your presentation that didn't occur during your rehearsals. Technical issues with your computer or bandwidth, people asking questions or making comments, etc.
5. Postmortem: Record and review your actual presentation.
Learn from your mistakes and don't repeat them. In my recent presentation I wished I had minimized the "Stop sharing" strip at the bottom of the screen. Additionally, next time, I would consider raising my video camera so I'm looking straight into the camera rather than down at it.