Anchoring is a simple yet powerful technique. Anytime you find yourself in an intense or exciting state and there is some physical stimulation, such as a pat on the back or a hug, those two things become linked neurologically. We can use the natural state to our advantage. If for example your facing having to give a presentation and you're feeling anxious, do this technique.
Think of a time when you felt really confident, or excited, or very happy or really in your flow or "the zone" ie the opposite of how you feel when thinking about the presentation.
See that event (the real positive one) in front of you and at the peak of its intensity, touch your thumb and forefinger together for a few seconds.
Break state for a few moments, ie move do something different.
Again see the event, at the peak if its intensity press your thumb and forefinger together again just until the intensity starts to drop.
Repeat this a few times.
Now, the next time you push your thumb and forefinger together you'll go back to that positive state, feeling confident or in the zone.
Repeat this a few times, now you've created an anchor.
Now, just before your next presentation, press your thumb and forefinger together and you'll anchor back to that positive state, getting you over the initial nerves that can cause a problem.
Its a simple technique as long as you practice!