Make sure that you think before you speak. I joined Toastmasters International about 9 months ago to help improve my public speaking, and I have improved. One of the best parts of our meetings is presenting a speech, but my next favorite part is Table Topics where you are asked to think about a given topic and respond for 1-2 minutes. It definitely helps you learn to think on your feet. So stop, pause and think, before you respond. After all, it's the right thing to do and it models the way for others.