Whenever you are preparing for that big speech or presentation, don't just go over it in your mind,
run through it in front of your camera! Use your phone or camera to video every practice session of your presentation.
Then, solicit feedback on your practice run from people you trust to be honest as well as constructive. After refinements, practice it again with video and gain insight into how you deliver your message as well as what that message is!
It's not about being "perfect." It's about making PROGRESS!