you can try using bubble gum,you brain will think you are eating then you will dont get nervous.

As odd as it is, I might try it.

I have the same type of problem. My classmates know me as one of the most intelligent people in the classroom, but I have a tendency to stutter, therefore making it look like I can't read out simple words, and it ruins the power of the speech. Just the other day we had to do a creative writing activity. My story was really good and I was super confident; but I stuttered a lot while reading it aloud and the story wasn't as powerful as I had intended it to be. I have my ways of bypassing this though. Before I speak I push my palms together as hard as possible, It seems to work. Relax yourself and imagine that you're speaking to an empty room. Hope this helped!
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This is also a problem I have. When this feeling occurs in me I just put my self in a rebellious mood. I make myself angry, so that I don't really care about what's going on around me and it makes it feel like nobody is around me.

Okay. I try to relax myself but I just can't for some reason. I do like the idea of imagining the room is empty, though. I might try it next time.

ignore the audience, just ignore all of them. don't mind what they might think of you, just go on with what you're saying this is pretty hard to practice, but you'll get the gist of it.

All I can say is this ^^^, believe me I used to pantshitting terrified of speaking publicly, but if you have the nuts (or maybe not Idk you) to put yourself on the stage and they can only chat shit behind your back, then you are badass and they are basically trash.

A lot of people above are talking about actual public speaking which is a hole other post but as for confidence just focus on the message you're trying to get across which I know sounds easier said than done but I know you can do it if you put your mind to it.

The trick is not to give a shit.
8/

^
Pretty much this. Also, don't let your mind wander, just focus on what you want to say. As mentioned before, looking at someone and imagining that you are only talking to him/her also helps (switch people regularly to make it less awkward).

Don't do this, it's unprofessional.

Also a good tip my english prof told me is that if you are to point at something in your presentation, use a laser pointer it makes you look better.

And if you need to point at someone directly (when answering questions etc), never use your finger. Point at them with a pen instead, it makes the action less personal and demeaning. (His words not mine)