Also, determine your total obligation before agreeing to anything. Don't give credit-card information to strangers over the telephone. Furniture delivery delays. Get an exact date. If the merchandise doesn't show up by that date, you would then have the right to cancel.
Free vacation offers.
Later the vacation is not as free as you thought. When shopping by mail, you're always taking a risk. When the offer sounds too good to be true, it probably is. What you'll get is information about how to rip someone else off the way they just cheated you. Federal law only protects you if you sign the contract in your home or somewhere other than the normal place of business.