List of tricks you probably don't know, ranging from "Take your bananas apart when you get home from the store. If you leave them connected at the stem, they ripen faster." to "De-fog your windshield: Buy a chalkboard eraser and keep it in the glove box of your car When the windows fog, rub with the eraser! Works better than a cloth!"
A lady at the post office taught me this trick and I have realized very few people know about it! You can turn a flat rate envelope into a pouch to increase the capacity. It holds more than a small flat rate box ($5.80) and about as much as a medium ($12.35) for only $5.60. So worth it! I do this all the time! Just fold the bottom both ways, and flatten it out from the inside, folding the corners and taping them up into a rectangular bottom. Secure with lots of tape. Happy shipping!