I am considering doing a presentation soonish, may even record it if I can, or even a documentary in my free time.
Tips? Be friendly and easy to listen to, no on likes listening to the boring chemistry teacher. Be lively, enthusiastic, passionate, etc… these will all come through in your presentation.
If you have enough yoyos, try and do a short workshop after maybe but if you don’t have enough then don’t do one since some may feel left out.
If you do talk about the history and mechanics of the yoyo then make it short and sweet, unless you are asked about it.
Make sure you mix it up. Have a good variety and don’t spend too long on one subject.
All in all though if you have fun, then it is likely that they will too.
Good luck.