Advice on selling a watch

Guys, I was wondering if you guys could give me some advice, or insight on selling
my first watch.   I have never ever sold a watch of mine ever. But am looking to 
maybe sell a few that never get worn or are too big for me. However, I do not know
how to go about things really. 

I see you guys have done it, but how does it work honestly?

Do I just put up the info on the watch, followed by pictures and how to pay for it?

How does the Paypal work? And what about shipping? ..Should I ship only in the U.S.?
Or also allow for international?

Just am looking for help? And any would be much appreciated.