To expand on listening to your gut instinct: I find taking a "trust but verify" approach useful. Take the time to dig into what your instinct is telling you, try to match it up in words to your hiring criteria (which should go beyond technical stuff, including capturing whether or not you'd want to work with the person), and compare against other candidates to check you're being consistent. For instance, you don't want to unfairly penalise someone for being loquacious just because their interview was right before lunch and you were getting hungry, whereas you enjoyed interviewing the similarly talkative candidate that happened to be interviewed just after lunch.