I've a note on presenting guidance I make a point of reading whenever I'm putting something together, I figure it would be useful to others too:

( whether I remember to read the advice, and follow the advice, is another matter entirely - feedback always welcome )

Recommended reading

Before you start reading, an excellent summary of most advice you'll receive is in Zach Holman's "The Talk on Talks", which is here https://www.youtube.com/watch?v=YVb2GsJHejo ; watch that, it's about fifty minutes long. Then visit Zach's site at https://speaking.io/

Now you've got an overview, concentrate on the overall format using How to give an Effective Presentation: https://qz.com/work/1110377/how-to-give-an-effective-presentation/

This presents the idea of how to structure the talk overall... and how to get your ideas together. I would emphasise this, I still struggle with trying to put too much in, spending days on research, and then realising I have a 90 minute presentation for a fifty minute slot. The sooner you can determine what is and isn't in the talk, the more time you'll have left to spend on making the most of what's in the talk.

If you want to be above average then avoid all of the "anti-patterns" Troy Hunt mentions in this article... a bit of preparation and avoiding very basic pitfalls can take you a long way: https://www.troyhunt.com/speaker-style-bingo-10-presentation/

For a step beyond that, Thom Langford has written a good three part guide to presenting, this is worth working through:

Part 1: https://thomlangford.com/2018/05/18/the-art-of-the-presentation-part-1-of-3/

Part 2: https://thomlangford.com/2018/05/30/the-art-of-the-presentation-part-2-of-3/

Part 3: https://thomlangford.com/2018/07/20/the-art-of-the-presentation-part-3-of-3/

If you want the level beyond that then make the most of the transitions, moving on to the next slide on the right word can make all the difference, as described in this piece. However this does require considerable practice: https://medium.com/@saronyitbarek/transitions-the-easiest-way-to-improve-your-tech-talk-ebe4d40a3257

Confidence tips

Practice. Preferably in front of family or colleagues or friends, but if it comes down to it just practice in a room on your own with the laptop and a timer. That way you know the timing works, you'll at least have an inkling of what slide is coming next as you present - and if you can get any kind of audience they'll give you feedback on what does or doesn't make sense.

If you need confidence just before a performance... power pose with fists clenched... and by "power pose" I mean that rather silly looking stance Tory MPs adopted where they stood with their legs slightly too far apart. In that pose your body will automatically think you're about to enter some kind of conflict and boost you with the right chemicals for a fight.

Try that with this idea, mentioned to me by my first mentee for BSides London, just imagine that the audience are penguins... flapping and squawking away, or waddling down to the water's edge for fish. It's silly, and nonsensical, but if it works it puts a smile on your face before you walk out there to face everyone.

And one last point, if you're an introvert, as per this tweet: https://twitter.com/KevinGoldsmith/status/963850794440187904, presenting gives you something to talk about with people, rather than having to navigate the morass of small talk.

The Presentation Itself

Just one piece of advice for this so far, look at how often you move around the stage, and the impression that can give to an audience. Essentially, according to this article by Simon Raybould, moving around more makes your more approachable, but less authoritative: http://presentationgenius.info/presentations-and-moving/ .

And from personal experience, make the most of people's immediate enthusiasm right after the presentation to hand out business cards and make connections.