I couldn't believe how easy it was to print shipping labels with PayPal. It is a heady experience.

First you sign-up for PayPal. Once that is done, you don't even have to register with the Post Office!!! You just either follow the link from your eBay sale/payment or the link from your PayPal receipt, and type away. You print the label on any regular sheet of paper, like the common 8-1/2 x 11" sheets. Or you start on this page if you have no receipt:
https://www.paypal.com/shiplabel/create/
You are automatically charged the postage fee from your PayPal account, and PayPal pays the Post Office the fee. So simple.

No more standing in line at the Post Office. Reduced rates. Free tracking. You can drop the parcel off at any street corner postal collection box. You can also buy insurance as you generate the label.

Long ago I had prepared this Guide for eBay about PayPal shipping labels. Good introduction:
http://www.ebay.com/gds/Intro-to-Printing-PayPal-eBay-Shipping-Postage-Labels-/10000000004429200/g.html

Robert