Not a talk specific tip, but just for presentations in general, the more you want the talk to come off as casual and not rehearsed the more you need to rehearse

Not a talk specific tip, but just for presentations in general, the more you want the talk to come off as casual and not rehearsed the more you need to rehearse. Don't just read it over and over, but give the talk to the mirror, a chair, your dog, etc. Best of luck. I've found that the lead up is actual worse than actually presenting. 10 to 20 seconds in, you'll feel fine.