If you include your business card in the envelope along with your sales literature, attach it with either a staple, clip or 3M Post-It glue (so it will peel off easily ... available in most stationery stores). Too often I open an envelope, take out the literature, and toss the envelope without realizing there was a business card stuffed all the way at the bottom. Waste of money for the mailers, since many times I'll keep the card long after I've tossed the other stuff. Extra cost of the clip: less than a penny (it costs less than the card).