When you are doing a deal, or showing someone your product, try to sit next to them. Sitting next to people puts you on their side, so you are working together. When you sit across, it feels more like a transaction and a negotiation.
When I tutored kids I always tried to sit next to them, or on the same corner of the table. This is a supportive position that lets them know I am there to help, not to yell at them. The same seating is helpful when you meet your customers.
Where do you position yourself when you meet with customers?