How do you mental prepare for a class presentation?

How do you mental prepare for a class presentation? The heart pounding. The sweaty pits. The sweaty forehead. You know you are about to be put on the spot and your stutter will be thrown out for the world to hear and judge. You know and think that you are about to sound like an idiot and gain everyone's pity. I don't know. I have one tomorrow and I am just hoping and prepping so that I can hopefully ensure that it goes relatively smoothly and this curse doesn't screw it up for my teammates. Edit: Thank you all so much for your replies. I just did the presentation. My group mates went more into detail on their parts while I rehearsed lines I made for my self over and over again in my head. I can't talk on the spot in front of a crowd and not stutter, so I only spoke basic. I stuttered kind of but overall, it could've been a disaster and it wasn't a catastrophe. It went "okay", which I will take!