The book Telling Lies: clues to deceit in the marketplace, politics, and marriage by Paul Ekman tells on page 141 how to lie successfully:
The liar could also use the Stanislavski technique, and if so there should be no signs that the performance is false, because, in a sense, it won’t be. The reliable facial muscles would appear in such a liar’s false expression because the liar feels the false emotion. The line between false and true becomes fuzzy when emotions are produced by the Stanislavski technique. Even worse is the liar who succeeds in deceiving herself, coming to believe her lie is true. Such liars are undetectable. It is only liars who know they are lying when they lie who are likely to be caught.
Ekman had just been describing “three ways in which concealed feeling may leak: micro expressions; what can be seen before a squelch; and what remains on the face because it was not possible to inhibit the action of the reliable facial muscles.”
Most people feel like they can detect a lie when it is presented to them, but Ekman’s experiments have proved that most people are easily fooled most of the time. There are very few people who have consistently proven successful in detecting even the most pedestrian of lies. When a professional liar, such as an actor, has any time at all to set up his mental performance it would probably prove impossible for even a sophisticated lie detector to spot a lie without knowing with considerable clarity the subjects being discussed. It is therefore possible for actors to rise to high political office, especially if they have been portraying politicians, because they are well versed in the necessary postures to present to the public. Also, because of their trade they are comfortable being observed and scrutinized by people, so they are the perfect liars. This isn’t necessarily a bad thing, because sometimes it is necessary for politicians to lie. It is only bad when they do the wrong things for the wrong reasons, and it comes to a bad end.
For almost everyone it is far better to be absolutely truthful all of the time because lying will usually get a person into far more trouble than it will get them out of. Heads of sovereign states, and their embassies are forced by circumstance to be outside of the law in their relations with other sovereign states, because there is little in the way of enforceable law to constrain them. That game is one of pure power with lying being the order of the day to maintain the peace, with the ultimate recourse to war when diplomacy fails.