Hi, the best way is to first empathize with the person stuttering, as even though it may be frustrating to hear them take a long time to get out their thoughts they are a million times more frustrated than everyone else is, as a stutterer its infuriating to not be able to speak sometimes. After that alot of it is just paying attention to what they are saying, its like dealing with any other disability or impairment, a little patience can go a long way!