Pass 4 - Le Tourniquet
These two simple rules of magic from the book Modern Magic are applicable in many other areas of deception: 1) Don't let the person about to be deceived know what's going to happen, and 2) Don't do the same thing twice in a row to the person about to be deceived.
Of course there are exceptions to these two rules, but most supposed "exceptions" are actually lies. When someone about to deceive you says they're going to tell you exactly what's going to happen, or says they're going to repeat something for you... they're almost always lying.
This is also true for acting. As Dennis Hopper related in an NPR interview when early in his career he asked James Dean for advice:
Modern Magic, Chapter 1 - Introductory Observations:"He said, 'Don't worry about emotion. Learn how to do things: Smoke a cigarette, don't act smoking a cigarette. Knock on the door, then you see they have a gun in their hand, then you react.' Basically, don't indicate. Do something, don't show it. Don't anticipate," Hopper recalled.
"The first rule to be borne in mind by the asperant is this: “Never tell your audience beforehand what you are going to do.” If you do so, you at once give their vigilance the direction which it is most necessary to avoid, and increase tenfold the chances of detection. We will give an illustration. There is a very good trick (which will be described at length hereafter) in which the performer, after borrowing a handkerchief, gives it to some one to hold. When it is returned, it proves to be torn into small pieces. It is again handed to the holder, who is instructed, in order to restore it, to rub it in a particular manner; but when again unfolded, it is found in a long strip. These effects are produced by successive adroit substitutions, and the whole magic of the trick consists in the concealment of the particular moment at which each substitution is effected. Now, if you were to announce to the audience beforehand that you were about to cause the handkerchief to appear in several pieces, or in a long strip, they would at once conjecture that the trick depended on an exchange, and their whole vigilance being directed to discover the moment of that exchange, you would find it all but impossible to perform the trick without detection. If, on the other hand, you merely roll up the handkerchief, and ask some one to hold it, the audience, not knowing what you are about to do, have no reason to suspect that you have handed him a substitute; and when the transformation is exhibited, the opportunity of detection will have already passed away.From the book Modern Magic - A Practical Treatise on the Art of Conjuring by Professor Hoffman (the pseudonym of the barrister and amateur magician Angelo John Lewis), published in 1876.
It follows, as a practical consequence of this first rule, that you should never perform the same trick twice on the same evening. The best trick loses half its effect on repetition, but besides this, the audience know precisely what is coming, and have all their faculties directed to find out at what point you cheated their eyes on the first occasion. It is sometimes hard to resist an encore, but a little tact will get you out of the difficulty, especially if you have studied, as every conjuror should do, the variation and combination of tricks. There are a score of different ways of vanishing a given article, and as many of reproducing it; and either one of the first may be used in conjunction with either of the second. Thus, by varying either the beginning or the end, you make the trick to some extent a new one. The power of doing this readily is very useful, and among other advantages will enable you to meet an encore by performing some other trick having some element of similarity to that which you have just completed, but terminating in a different and therefore unexpected manner."