Have a thorough knowledge of the mattresses you carry as well as a thorough knowledge of those your competitors carry. Get your customer to lie on your beds for at least 30 seconds first on their back and then 30 seconds on their side. Don't put your customers on too many sleepsets. Beyond several, they become even more confused. If you carry brands that are not readily recognized, don't tell your customers that those manufacturers prefer to advertise less in order to put more money into the quality of their sleep sets.
Most customers enjoy quality products that are heavily advertised.
On the subject of floor samples, never show them first to your customers. Whenever a customer calls about a brand you do not carry, never reply. We don't carry that brand. Instead tell them what you do carry and do your best to get them to come into your store. Instead of overcoming the customer's concern, first confirm it as a need, then go on to support the need.