Fellow speaker,
When you are about ready to end your speech, signal your audience in some way. It could be a phrase you use, or a summing up of main points, or some other method. Whatever you do, once you have signaled the end of your speech, make sure to end in a timely manner (i.e., in five minutes or less). The one thing an audience can not stand is a speaker who indicates they are going to end and then never does.
Signaling,
Tim