The most practice I've had with this technique happened with my first son's mom. She could regularly read a person's thoughts and she felt that it was always her business to know what I was thinking about. It didn't take long to know when she was trying it - she acted exactly as I wrote in the previous paragraph. I've had others do this and they all had a similiar look so I think I'm on to something. Whenever she would get the "stare" going, I would picture a brick in my mind. Sometimes it was an entire brick wall. I would concentrate on that brick and I probably had that same blank look in my eyes while I was doing so. By thinking about nothing but a brick wall you create a barrier between the person and yourself. In time, all I had to do was think "brick" and I would instantly have a force-field surrounding my thoughts. She would afterwards comment on the fact that I had a strong mind and she could never tell what I was thinking. Then she would ask what I was thinking and I would always tell her it was a fork. It worked every time and she rarely caught me off guard.
Try picturing a brick in your head right now. It should be sitting just inside your forehead and it's not hard to do. If you concentrate just a little harder you'll then realize how strong that brick really is. Turn it into a brick wall and nothing will get through. That's all there is to it - you now know how easily you can fend off a psychic attack from close range. It's amazing the little things the mind can do and it sometimes sounds too fantastic to be true but once you've used it and seen how well it works you'll begin to believe in a lot more.