In a blog I posted a few days ago I made th epoint of the importance of sending a high impact email immediately after meeting with anyone - a prospect, a center of influence or an existing client. It was my contention that your quick and thoughtful response would demonstrate your sincerity and dependability.
One additional thing i should've mentioned at the same time is that the email enables you to demonstrate that you were really listening. Not just nodding your head, not concentrating on your own response, but actually paying attention to the other person's words. All too often during a conversation, our mind skips ahead to begin formulating a reply without hearing the other person's completed thoughts. But when you take the time to craft your follow up email, you can reiterate the salient points that were rasied during your conversation - not only to show that you were listening but to offer some insights regarding 'next steps' in response tot he conversation.
Don't jump to conclusions when someone is talking to you (I confess that this is one of my worst habits! ) but rather give the person the respect they deserve by allowing them time to speak before you jump in with your comments and opinions.
As so many people remind us - we have two ears and one mouth: that's the best equation for a good conversation. Listen twice as much as you talk!