Show you are paying attention. Keep your eyes on the person who is speaking. Don’t look away, even for a second. The speaker will probably look away frequently, as that is what people do when they are thinking.
HELPFUL HINT:
Demonstrate that you are paying attention by nodding or interjecting with statements like: "I see"; "I understand"; or "Of course". When interacting with someone remember the old saying: "They don't care how much you know until they know how much you care."