I hated public speaking for years. I worked for a large construction company and was put on a 'presenting with excellence' course. I was dreading it and was trying to find a way of getting out of it. I ended up on it, in a unfamiliar environment of a fancy london office block with 15 other people I'd never met. Nightmare! I can't remember the name of the guy running the course, but he was excellent. He specialised in teaching live TV presenters to cope when things were going wrong. I learnt a massive amount over the two days. Anyway, I'm no tutor and not very good at it, but these are the things I took away from the course :
Any nervousness is an obstacle that your brain is creating and it's going to make everything more difficult. It's like learning to abseil, the more you do, the more natural it feels. Also, like abseiling, you still need to start with a proper plan. Just because the nervousness has gone away, you can still f#cuk it up - know your material and be prepared with your structure.
Build trust in your audience. Some self-deprecation helps. It's far better to expose some weakness early and then really deliver with the detail & knowledge, rather than come across as a super-confident professional presenter and then fall apart when you get into the detail. You can see this with some of the most relatable people. They start the presentation with some slightly embarrassing story, then get stuck into something interesting and only later do you realise they're actually the world-authority on something. That seals the trust deal.
Learn about 'right side brain' visualisation technique. This is about painting a picture in your audience's mind. Using words like 'Picture this....', 'Imagine you are...' etc. This is a great way to distract the focus from you. Your words are building something in their head. They've stopped looking at you and started thinking. This is a massive thing if you can get it right.
Get rid of the annoying habits. Unfortunately, you need to be brutal with this. On my course, on the second morning once everyone had built into a team and it had started to become a bit of fun - they put the presenter at one end of the room and everyone else at the other. They started speaking and we were encouraged to shout out faults! "Too quiet", "EEERMMM", "Too fast", "Too fast", "Too fast", "Too fast", "Pause NOW", "Pause NOW", "Get your hand off your face!". I'm not sure how you'd do this by yourself, but it was an incredibly quick way of fixing it.
If you want to appear intelligent, use simple words to explain complex things. Not complicated words to explain simple things. It's about getting a message across, not a p1ssing contest.