On a lark I put together a mentalism act to perform for pagans at a family oriented Beltaine festival that happens to be a yearly event close to my house. I practiced and had a solid fifteen/twenty-five minute routine. My best affect was my finale. Pieces of paper were handed out to the crowd, the crowd was asked to write a visual image. I picked an easy on the eyes spectator to pick a piece of paper out of the bowl they were placed in. The young lady and I stood back to back as she drew the picture on a clip board as I did the same on my clip board. We both had pictures of black cats with witch's hats at the end!
It was right out of a Banacheck video. It worked very well.
I did that once and it worked brilliantly. I did other things once that worked but I could have done them better with more experience. This trick was bang the first time. I recommend it - as someone who who has a one mentalist performance (with a large audience) under his belt.
The Banachek version is good (although I had some quibbles about the patter, and there was a risk of pulling someone out of the audience who might mess up the effect), but there's a similar effect on one of Richard Osterlind's videos that involves a little less risk of mess-up AND that can be readily performed simultaneously with two spectators (and two different drawings).
I have given speeches in which I end with mentalist effects. I've done one effect that is number-based and one newspaper prediction trick. The number trick turns out to be nearly sure-fire, and the newspaper trick is SUPPOSED to be sure-fire. The first two times I performed the newspaper trick, however, the trick got messed up, in ways that I never foresaw. On one of the occasions, I was able to recover.
There were differences between the tricks. One of them was introduced (not by me, but by the person introducing me) as a magic trick, which immediately put the spectators into a suspicious mode. A better introduction is to say that it is an "experiment," or "I would like to try something," and avoid the use of the word "trick."
Another difference between the two tricks is the degree of audience interaction. In the number trick, the spectator has to ORALLY give me a number from a particular range of numbers AND NOTHING ELSE. In the newspaper trick, the spectator has to give me a number IN WRITING from a particular range of numbers AND some other modest information. It may not seem like much, but these little extra pieces of information, plus the introduction of writing, can cause all sorts of trouble, especially if a spectator is paranoid or wants to be a wise guy. Some spectators try to hide what they've written, others have crappy handwriting, others can't seem to comply with simple directions beyond doing one thing.
Perhaps there is a mentalist's axiom that, the more you give the spectator to do, the more likely there is to be a foul-up.