I spent yesterday evening at a "Speed Venturing" event. Entrepreneurs got 12 minutes to pitch their business to potential investors. Most chaffed at the time constraint, especially when the 'winners' had to summarize their business in 1 minute. Hearing their stories during the un-timed networking, I could tell why: most were technologists and engineers that had really cool concepts. They innovated around some really hard constraints and the results were worth talking about. Most could talk for a half hour without even getting started.
But I'm still a fan of the 12 minute constraint. (As were the investors.)
Constraints foster the best creativity. When you have to get the point across in a few minutes, you come up with the most ingenious ways of doing it. Even if you have an hour for a pitch, I'd practice getting it done in ten minutes. Concision makes you crisper and easier to understand.
Practicing Concision Materials: a timer and a whiteboard.
Identify the question you're answering. Write it at the top of the whiteboard: constantly seeing it will give you a clear standard for editing your answer.
Take your business plan (or other documents) and pick out the important ideas that answer the question. Write these, bullet point style, on the whiteboard.
With all your potential ideas on the board, answer the question a few times out loud without the timer. Try a few different arrangements and begin to group the ideas in ways that sound connected. You're trying to build a logical order.
Introduce the timer first as a diagnosis tool. Give your best answer and see how long it takes; then start cutting and rearranging. Set the timer to countdown mode and practice a few more times. You're trying to hear what can be left out without leaving the question unanswered.
Concision is not the same as speed. Talking too fast can make you completely unintelligible. Tease out your most important thoughts and express them with the fewest words possible, leaving time for appropriate pauses and emphasis. Concision should help you be understandable and convincing.