Suspend judgment. Focus on what they're saying rather than your analysis of it. Listen now, form your opinion later.
Make gestures. Use your body language to make it clear that you are involved and listening. Keep eye contact and make the occasional nod of recognition.
Ask open questions. A good listener will ask questions that encourage the speaker to delve deeper. Prompting them to identify the highlights of a meeting will be far more effective than 'Did you think the meeting went well?'.