Opening jokes are for comedians only, and you aren't one
Each person's talk should be between 5 and 8 minutes. Therefore, a group of 3 will take 15 to 24 minutes. Each person can use no more than 5 transparencies. While it is good to provide general context, at least one aspect of your presentation should go into the scientific details in some depth. Using a figure from a scientific paper is an excellent way to begin this process.
Use 1 figure per minute at most, & 1 figure per 2 minutes at best
Make every figure interesting
Simplify your figures, and then make them simpler.
Explain your figures in detail (including defining axies)
Use figures as a memory (numbers & words) crutch
Don't read from text figures (face audience & paraphrase).
Use a CONCLUSION or SUMMARY figure to show you're done
Use analogies that are familiar to the audience
The best defense is a good offense (address problems and limitations)
Ethnic, sexual, & religious comments are never acceptable
Coarse words (including ain't) are never acceptable
Double entendres are never acceptable
Both abject humility and arrogance are counterproductive
Never ridicule anyone
Carefully listen to questions before answering
Acknowledge the validity of an appropriate question
Don't answer a question that you don't know
Don't take the bait of an inappropriate question