Meditation is all about practicing control over the talk in your head. A lot of that talk is worry, over planning, or managing your image when you don't want to; the book The Curse of the Self* describes the many ways our own thoughts undermine us.

Some people say meditation is about "not judging" or "being present", and that is indirectly true. The point is shutting up the worrying, planning, judging voice until you consciously desire.

The advantage is plain, I think. If you aren't worried about your self-image, you can consciously or intuitively get involved in conversation. Or give a speech. Or avoid experiencing Camus' Sisyphusian Absurdity. Whatever.

How to meditate: Just sit comfortably, with good posture, close your eyes, and concentrate on some physical sense. Breathing is the most common and recommended. (EDIT: It's not advised that you use your heartbeat, since you could speed it up by accident.) Whenever a thought comes along, immediately return to the physical sense observation. Always return to the physical sense. You can't argue with yourself: "No, I'm meditating." It will just start a chain of thoughts. "If I'm meditating, why am I thinking?" Etc. Just stay focused on your breath. If you have a thought, let it pass.

It's important to remain alert (unless you're meditating to sleep), and a successful meditation session should end with you feeling awake. Lastly set a timer. Start off with ten to fifteen minutes. It's going to seem like a long time to begin with.

I've found it very helpful. I advise meditating (or short naps) before doing anything likely to be stressful, pua stuff or not.

One other thing, don't waste your time on hippy books about meditation. I've said everything you will ever need to do it. If you don't like money and do buy a book, research the author and make sure they're a real doctor or otherwise scientific about it.

*: The book doesn't go into much detail as far as advice goes. It does advise meditation, though.