Is it a good idea to memorize your speech? And how do you memorize a presentation? I come down pretty strongly against the idea of memorizing speeches. For starters, it's hard to do even in an ideal situation. But when you're standing up in front of people, especially if it's people you don't know or a larger group than usual, you're going to feel nervous when you're nervous. Your body's telling you run, your brain actually shuts down your ability to recall information quickly and easily goes out the window.
So I don't recommend trying something that is not only hard, but 10 times harder than normal. It sets you up for failure. The other problem with memorization, is that when you stumble over a word, it's like you've run over a speed bump and everything falls apart. It makes it seem like the ripping sound. Have a record player needle off of an old record player, the whole presentation comes screeching to a halt. That's why it's so obvious when a Broadway actor flubs a line.
It's just somewhat jarring. I recommend you try to have a more natural conversational way of just speaking with people. That's why the easiest thing for most people most the time is to simply use notes, a simple outline. That way, you're not trying to get every word just write a set order. you're focused on the ideas, and you're conveying the ideas and you're using whatever words come to you, much less stressful on the memory, therefore, lower probability of messing up