When I was new in sales, I was concerned others could tell. So, I focused on letting them know how knowledgable I was - which meant I talked... alot! This was a turn-off for alot of customers. Then I began to evaluate my communication process and learned several things:
1-People want to feel important. This translates to let them do most of the talking and you do most of the listening. Whether they are talking about their kids soccer game, work, or what they know about the home-buying process, let them speak. Repeat parts of what they say back to them. Write it down! Be interested!
2-They don't care what you know until they know you care. If you've never met the person before, you are a complete stranger. Bombarding them with how much you know doesn't mean alot. Find out who they are. What are their thoughts and concerns? Be observant. Does the person look happy or sad? Having a good day or bad day? If the customer feels like you see them as a person instead of a business transaction, they are more likely to place their trust in you. Which translates to doing business with you.
3-Don't interrupt! Even if what your customer is saying is completely off-based or incorrect, let them speak! (of course, if someone is being just plain rude, I have the self-respect to end the conversation but that's not what I'm talking about here) I find myself interrupting more when I'm in a hurry or I'm trying to get alot of information to them. But let's face it. NOONE likes to be interrupted.
I have to constantly remind myself of these 3 basic principles though I've been in the business over 12 years now. Going back to the basics and remembering the art of people-skills keeps me sharp and my clients happy.