Preparatory conditions include the status or authority of the speaker to perform the speech act, the situation of other parties and so on.
So, in order to confirm a candidate, the speaker must be a bishop; but a mere priest can baptize people, while various ministers of religion and registrars may solemnize marriages (in England). In the case of marrying, there are other conditions - that neither of the couple is already married, that they make their own speech acts, and so on. We sometimes speculate about the status of people (otherwise free to marry) who act out a wedding scene in a play or film - are they somehow, really, married? In Romeo and Juliet, Shakespeare has no worries, because the words of the ceremony are not spoken on stage, and, anyway, Juliet's part is played by a boy. (Though this may make the wedding scene seem blasphemous to some in the audience.)
In the UK only the monarch can dissolve parliament. A qualified referee can caution a player, if he or she is officiating in a match. The referee's assistant (who, in the higher leagues, is also a qualified referee) cannot do this.
The situation of the utterance is important. If the US President jokingly “declares” war on another country in a private conversation, then the USA is not really at war. This, in fact, happened (on 11 August 1984), when Ronald Reagan made some remarks off-air, as he thought, but which have been recorded for posterity:
“My fellow Americans, I'm pleased to tell you today that I've signed legislation that will outlaw Russia forever. We begin bombing in five minutes".
Conditions for execution
Conditions for execution can assume an exaggerated importance. We are so used to a ritual or ceremonial action accompanying the speech act that we believe the act is invalidated, if the action is lacking - but there are few real examples of this.
Take refereeing of association football. When a referee cautions a player, he (or she) should take the player's name, number and note the team for which he plays. The referee may also display a yellow card, but this is not necessary to the giving of the caution:
“The mandatory use of the cards is merely a simple aid for better communication.”
In knighting their subjects, English monarchs traditionally touch the recipient of the honour on both shoulders with the flat side of a sword blade. But this, too, is not necessary to the performance of the speech act.
At a simple level these show that the speaker must really intend what he or she says. In the case of apologizing or promising, it may be impossible for others to know how sincere the speaker is. Moreover sincerity, as a genuine intention (now) is no assurance that the apologetic attitude will last, or that the promise will be kept. There are some speech acts - such as plighting one's troth or taking an oath - where this sincerity is determined by the presence of witnesses. The one making the promise will not be able later to argue that he or she didn't really mean it.
A more complex example comes in the classroom where the teacher asks a question, but the pupil supposes that the teacher knows the answer and is, therefore, not sincere in asking it. In this case “Can you, please, tell me X?” may be more acceptable to the child than “What is X?”
We can also use our understanding of sincerity conditions humorously, where we ask others, or promise ourselves, to do things which we think the others know to be impossible: “Please can you make it sunny tomorrow?”