1. Design the talk for the audience
2. Prepare thoroughly and rehearse the talk
3. Produce clear, legible slides
4. Arrive early and check the lecture room
5. Speak slowly and loudly
6. Be enthusiastic about what you say
7. Look at the audience as you speak
8. Don’t fidget with the slides or the pointer
9. Finish on time (or early)
10. Answer questions courteously and concisely, and admit if you don’t know the answer.
(Taken from Nicholas Higham's book: Handbook of Writing for the Mathematical Sciences)