Your prime directive
If you learn just one thing about public speaking, let it be this: your prime directive as a presenter is Don't Be Boring.
Most speakers think that their topic is the most important part of their talk, but they're wrong.
A few days ago I was at a conference for students featuring introductory talks on a number of topics. Nick Quaranto gave a talk on TDD. I've been doing TDD for years now, have read about it in depth, and have discussed the practice to death with lots of smart folks. I'm am extremely familiar with the topic.
Nick's talk was intended for folks that had never heard of TDD before, and was completely basic. I learned literally (literally!) nothing from it.
And you know what? I was completely entertained for the whole damn thing.
Nick had well-designed slides, entertaining gifs, and excellent pacing and energy. I laughed my way through his talk and gave him the hearty applause he deserved. I didn't learn a thing from him, but he made the concept interesting through his delivery.
THAT is what you should be shooting for when you stand up in front of a group of people.
What you talk about is many times less important than the way you present it. Never forget that.