Three more tips for important talks that you want to nail:

1) Go through your slides and remove as much math/code as possible, until you have a minimal amount of math/code. Now, go through your slides and remove as much text as possible, replacing it with images.

2) Rehearse your talk until you can do it without ever looking at the slides. e.g. practice it under your breath in the subway.

3) Do a practice talk in front of a few friends, a week before your talk. Incorporate their feedback.

I did this recently for the most high-profile talk I've ever given (How to do "AI" in 2013: http://new.livestream.com/gigaom/gigaomroadmap/videos/579403...), and I feel like it was my most polished talk to date.