Weigh packages to ensure the proper postage. When you're packing a box of goodies to send off, be sure to cushion the contents with something, such as bubble wrap, newspaper or Styrofoam peanuts. Use packing tape to secure your boxes - not string or twine. Be sure that the only addresses on your package are the delivery address and the return address. You may even want to put a slip of paper with both addresses in the package.
Nothing takes longer to deliver than a ticking package.
Any stamped packages that weigh more than 1 pound must be taken to the post office to send, due to air transport security rules.