I posted some fabrics for sale around Thanksgiving.
My suggestions:
Double check the morning you post, to be sure you have "a regular here" above your avatar when you comment on a topic. If you do not, all your time is wasted because your posting will be dumped.
State clearly which forms of payment you will take. (I got nagged about not doing paypal.) I have been sending fabric as soon as I received the check, m.o., or cash.
Edit the title line above each item as soon as you have a request for that item. Pictures can be deleted when that fabric has been shipped.
Expect some people to take a couple of weeks to get around to sending payment -- don't be afraid to remind them! (Or set a time limit.)
I found "first class" better than flat rate envelopes for up to 1 1/2 yards. Compare to save on postage.
Good luck!