Things I've learnt
Set the tone
The first things you say and how you introduce yourself determine how the audience will respond.
Think about your first words and the message and permission you give to the audience
Know your audience
Who are you speaking to? FInd out as much as you can about their background knowledge. Make useful assumptions about their likely behaviour. Adapt your approach to the people you are talking to
Check your stuff
Make sure you have all your props and they work. If you are using a.v make sure it works. Do you have spare cables? Carry a spare clicker
Use the right language
Think about jargon and use formats which are appropriate for your audience. Remember- other people are not the same as you!