Doing any routine that is a prediction has several problems to overcome (when I perform them, that is). There’s the issue of the fact that being able to see into the future is a bit too unbelievable, and if it were something you could actually do, using it to foresee a selected playing card would probably be pretty far down a pretty long list of things you’d do to demonstrate the ability.*
However, it’s a popular plot, and can register very strongly.
There are two particular pitfalls I try to avoid overall though. Firstly, I try not to have anything printed – I think this generally gives the impression that the outcome is always the same, and unless it is very, very clear in the presentation that every choice is utterly free, this is to be avoided.
The other thing I never let the spectators do is ‘change their mind’. Let’s say you are predicting which ESP symbol they are thinking of, via multiple outs. Offering the spectator to choose one, and then change their mind if they like, implies that the trick is never going to fail – that ultimately, their choice and involvement in the process is irrelevant to the success of your piece. As a rule, I think it gives intelligent spectators a place to start backtracking from.
So, I stress that they can not change their mind. I often phrase it like so… ‘I want you to decide on one symbol, and when I click my fingers, say it aloud. Once you have said it aloud, you can NOT change your mind, that’s the decision you have made.’
Just this small line will not give the spectator a starting point to backtrack from, and anywhere they might backtrack from is going to be incorrect. ‘I couldn’t change my mind, so maybe it’s always that one that is chosen… Or maybe I was influenced to pick that one… But what would have happened if I had said the Circle?’ That’s far more in-keeping with the modern presentation of mentalism, and (for me at least) makes a big difference.
*Eugene Burger has a PERFECT solution to this problem – he introduces a prediction as an ‘Inevitability’ that the spectator can’t avoid. This is the same effect, but gives a totally different approach to the prediction plot, and worth your study. It appears on his DVD ‘Exploring Magical Presentation’.