Interview with Winder Dairy

I Just wanted to write and let you know that i went to a interview with Winder Dairy today- i interviewed with a Bob smith! he is very nice. The interview was only maybe about 10 minutes long- he told me about the position more into detail. It is door to door sales and it is straight commission. Anyhow as i was interviewing i found and caught myself and it's a habit but, i found myself more than once saying "UM!" again it's a habit at the same time though i think that maybe affecting the outcomes of these interviews. Any advice, tips or idea's on that? i mean i know it's me that is doing it but anything you can think of that would help me not do that- probably not. any advice or anything you can offer would be great.