One tip I've found really useful over the past few years is to always try and include a "STAR moment" in a talk - where STAR stands for "Something They'll Always Remember".
Effectively it means try and have at least one memorable surprise or gimmick in your talk. If someone watches a dozen talks at a conference you want them to be able to say "Oh, I remember your talk, it was the one with ..." when they meet you in the corridor.
I deployed my pelican on a bicycle benchmark as a STAR moment last year and it was really effective: https://simonwillison.net/2025/Jun/6/six-months-in-llms/
At PyCon a couple of years ago I used a vibe-coded counter of the number of times I said "AI" out loud: https://simonwillison.net/2024/Jul/14/pycon/#pycon-2024.043....
Yup. This. As long as people remember you for something positive, you'll get a second speaking slot.
Personally it rapping and wigs. They both go down surprisingly well at tech confs!