Be sure of your facts and accurate about time frames. The points you are making will have the most impact if you can ensure their accuracy. Often, the times at which various events or decisions occurred are important. The more accurate you can be in making such references, the better. They appreciate short, concise messages.
People sometimes think the best way to make a point is to repeat the testimony of other speakers.
In reality, it often can be counterproductive because those in charge of the meeting are likely listening for as much new information as possible. This helps people more easily follow what you are saying as you deliver it. Further, it can be a good technique for expanding on your limited time at the podium. Experienced testifiers often deliver testimony in an abridged version of a longer piece that they hand out. This can be a valuable reference in your follow-up contacts.