I ship with USPS and will provide the express and priority mail shipping rate from their online price calculator when the shipping price is requested, but I'm a bit confused for when shipping is more expensive than the estimate from online I normally pay out-of-pocket with money from the sale itself, but what do I do when I accidentally overcharge the customer? (I luckily haven't done this yet, I have accidentally undercharged) Also, how can I make sure my shipping estimates are fully accurate?
I'm just really worried about keeping a good reputation for when I sell more / offer commissions more, and I want my reputation to be correct. (As I've seen overcharging on shipping being a problem in some bewares, but not the main point normally.)
I purchase the boxes at the post office when going out to ship, if that makes a difference.
Thank you in advance for any responses!