I don't mail many chips, but one thing that I do is to make sure that either my address or the receivers address is inside the package, too. The easiest thing to do is just use a return address label on the chip packaging...whether it's in a airtite, or a flip, or wrapped in bubble, or... That way if there's a genuine postal accident that separates the chip from the envelope, you might get the chip back.

When mailing 'stuff' I usually put it in one of the Tyvek priority envelopes, then put that envelope in the cardboard flat rate priority envelope. It protects the stuff from weather, as well as damage.

Great tips, Doug!