I think that you might be caught in a vicious cycle, you say it makes you really nervous making it difficult to even prepare for it. Being poorly prepared is my source of nerves when giving a presentation. So in not preparing you make your feelings worse.
This is what I do and it helps for myself:
-Prepare the presentation well in advance
-Have your slides give you hints as to what you should be saying
-Write out exactly what you want to say (don't include it in the presentation, this is just a copy that only you see) and put the slide headings / points above the relevant text. If you forget what you want to say you can look at your notes and easily identify what you should be saying. I don't recommend you just read the notes to the audience, I use them as a backup tool if I get serve nerves and get a mental block.
-Take your time, lots of people rush due to nerves.
-If at all possible insert a video / clip to demonstrate a point. Having them view a video allows you to relax for a while and recompose yourself.
-Run through the presentation to yourself 3-4 times (or more) to smooth out what you want to say.
-Don't drink alcohol/energy drinks/caffeine
-If you have the option give your presentation as early as possible. For example if 10 people are giving a presentation try and get in the 2nd position slot (I like to compare mine to one person before I present). If it's 2-3 people then I like to go first, i find it stops the nerves from escalating to an uncontrollable level.
-Change your perspective of those feelings. When I get nervous it's now an exciting feeling. Use them to get "PUMPED" for your presentation.
One problem I used to have was that I'd always feel like I was going to be sick, or be bursting for a doodoo. Come presentation day, I only eat food that i've eaten before and eat most days. I don't eat 2-3hours before the presentation (if there is nothing in my stomach /haven't eaten a dodgy kebab I can't be sick). It's probably a bit stupid BUT it works for me.
Good Luck