Although I'm no expert, I've read several accounts from interrogators, both current and former, that the most effective method is to gain the favor of the potential informant, by such ordinary means as conversation, having lunch with him, and interrogating him non-aggressively every day.

If one wants to get information quickly, to prevent an imminent attack, torture can provide information quickly, but it's a huge gamble that it will be accurate. If it isn't, the prisoner isn't likely to provide any reliable intelligence all, no matter what else is attempted.

The best information for preventing imminent attacks does not come from prisoners, but from civilians and informants sympathetic to us, who can provide reliable information and provide it quickly.