In the last 20 years, I've heard over 10,000 presentations. As I've taken in the good, the bad and the ugly, one mistake stands above the rest:

Most presentations move too quickly.

Think about it for a minute: When you want to learn something new, what medium do you turn to first? Generally speaking, you read. Why? Because reading allows you to move at your own pace. If a concept is difficult to grasp, you stop for a moment and reflect. If you still don't get it, you go back and re-read.

But when you're delivering a presentation, your audience doesn't have those luxuries. They can't (or won't) ask you to slow down. If you speak at a brisk pace, most won't take a few seconds to think about what you just said; if they do, they'll miss the following points they need to keep up.

This places the onus on you as the speaker to move at a pace that is comfortable for your listeners. This is easier said than done. Why? First, because you're nervous. People tend to speak faster when they experience anxiety. (Gets you out of there more quickly, right?) Secondly, if you're generally enthusiastic about your subject, you naturally pick up the pace. Of course, that enthusiasm is great. But left unabated, it will mitigate the value of your presentation.

So how do you fix the problem? By following these 5 tips:

1. Remind yourself to slow down

Write yourself a note and place it in your line of vision, reminding you to speak more slowly. You can also get a trusted audience member to give you a signal if you speak too fast.

2. Pause

When you ask a question, make sure to pause and count to three or four. This gives the audience an opportunity to respond mentally (or out loud, if appropriate). Do the same thing when transitioning between points or to stress an important idea. It's a chance for listeners to mentally "catch their breath", so to speak.

Those few seconds will seem like an eternity to you, but they are perfect for the audience.

3. Use repetition

The best teachers are masters of repetition. (Just think of how many times your parents had to tell you the same thing before you really got it.)

When you repeat main points, you slow down naturally. You also control what the audience is most likely to remember. You might try it at the end of your speech, or even at the end of each section (depending on the length of your presentation).

To emphasize a significant point, you might simply pause, say something like, "I'm going to repeat that", and then say it again. Another great repetition tool is to use phrases like "in other words" and "to put it more simply". These expressions allow you to teach a point in a way that is easier for the audience to grasp--again, giving them the chance to catch up mentally.

A word of caution: Be careful not to become overly repetitive, at risk of boring your audience. If possible, try out your presentation in front of someone who will give you constructive feedback.

4. Cut your material

Most presenters try to cover way too much in the time allotted. The fix? Cut out everything that's not essential to your talk.

Even if a presentation is great, the audience will only retain a few main points. Resist the urge to include something just because you think it sounds nice. Does it relate to your main theme? Will it majorly contribute to accomplishing your main purpose?

When in doubt, leave it out.

5. Practice, practice, practice

Speaking more slowly in front of a group doesn't come naturally. Like any decent skill, it takes mindfulness and repeated practice. Try recording yourself when you speak--not only in practice sessions, but when you do the real thing.

Seeing and hearing your pace in real time will increase your awareness and motivate you to improve.