Good tips, but I think you are missing a couple of the most important:
- open an online account with FedEx, UPS, or both. Print your shipping labels from home, prepaid on your credit card. This way you never need to declare what is in the package, and you don't have to answer to anybody when dropping off your package - just leave it with them and split.
- If possible, leave your pre-paid, pre-labeled boxes with your shipping dept. at work for their daily pickup (may not work with FedEx GROUND service, as that is treated differently than FedEx Express). The chances of you running into problems is infintely smaller if you package is being shipped from a business, and is mixed in with everything else.