At the scene of any hostage crisis, the two most important officials are the commander, who has authority over the entire scene and all the personnel involved, and the negotiator, who communicates directly with the hostage-takers. It is vital that these two positions are not held by the same person (Antokol, pg.134). The negotiator has to keep an objective point of view and remain calm, both of which can be difficult if he or she is simultaneously making command decisions. Also, one of the negotiator's most useful tactics is to cause delays by telling hostage-takers that higher authorities must be consulted before a decision can be made or a concession offered. If the negotiator is the highest authority at the scene, this obviously won't work.
The negotiator's first priority at the beginning of a negotiation is to gather information. A lot of information will come from other officers at the scene who have scouted the area or run background checks on the hostage-takers, but the negotiator can learn a lot from the hostage-takers themselves. The negotiator must find out who the hostage-takers are, why they are holding people hostage, what their demands are and who their leader is, if there is more than one. At the same time, the negotiator is paying close attention to the hostage-taker's responses, mannerisms and general attitude in order to create a rough psychological profile. This can give the negotiator some clues as to how the hostage-taker might respond to certain situations -- a negotiator deals very differently with a depressed, suicidal captor than with a cold, rational pragmatist.