When you sell something, how do you know in advance how much to charge for postage? Don't you have to know ahead of time how much it will cost to tell the person who is giving you money through Paypal?

You can buy a small postal scale. I bought my last one at Office Depot. The 1st one came from WalMart. The scale is very accurate. That is the reason I require zip; to figure out the shipping costs.

Thanks.
I guess you'd have to figure it all out ahead of time then, how much a yard of fabric weighs, etc.
I keep saying I'm going to sell some items but just can't get started. If anyone knows of a link to explain the process, that would be great! I'm just not good at figuring this stuff out and wouldn't want to make a mistake.

Ceil, if you discover that link, pass it along to me, lol. I learned by just doing it; also asked question along the way. This thread is a good start -- lots of good info here.

Using "refund" when it is not an actual refund is fraudulent and you take a chance of having your paypal account terminated.

Yes, maybe I'll just have to dive in and hope for the best! :)

Perhaps it would be a good idea to take the time to read all the information provided on the PayPal site - how to request and receive money online, how to send it, fees involved, different account types, protection provided and under what circumstances, managing your account balance, transfers in/out to your bank.

Everything you need to know is available there.

For shipping, the best option is flat rate envelopes from USPS. You can get the envelope for free, then stuff it as full as you can for $5 or so. The flat rate boxes are around $10. You can check it out on USPS.com. That's what I did when I was selling on ebay and I think I got 3 or 4 yards of fabric in a $5 envelope :)

Saw a post in the donation area of scraps that are being sent to Ukraine and they were paying postage of $59.00 by Western Union. Funds transfer is immediate (within 30 minutes).

I would be very leery of sending money via Western Union - it's the money transfer method of choice among scammers. I don't know what the Ukraine transaction consists of so I am not commenting on that.
But when someone asks you to send money by Western Union you can kiss it goodbye, along with whatever you were hoping to buy. Like throwing cash off a tall building.

I have been using Paypal for over 10 years and have never had a problem.