eBay
When I sell several items at a time on ebay, I schedule them so that they auction ends at about 9pm. If you pay up immediately, and the majority will pay within a couple of hours or so, I can get the item in the post the next day.

Stop waiting a day or so to pay because then I have to make two trips to the post office.
( sandettie light vessel automatic New Twitter - @bollocksreally, Wed 6 Apr 2011, 15:10, 5 replies)

And
The ones who pay just after you have got home from the post office
(insomniac-surfer oh go on then, just this once, Wed 6 Apr 2011, 15:47, closed)

And
the bastards who mark you down for postage costs when the Royal Mail stamp on the front matches the amount you charged them.
( brown-wings Made with three kinds of butter, Wed 6 Apr 2011, 16:09, closed)

I pack and weigh
everything before I list the item so I can be as accurate as possible with the postage.
( sandettie light vessel automatic New Twitter - @bollocksreally, Wed 6 Apr 2011, 16:11, closed)

Post was as described, slight damage to sense of well being and handle on reality. Would read from again A++++++++++++++++++++++++++++++++

(Bushcricket, Wed 6 Apr 2011, 16:20, closed)

I tend to.
Say everything will be posted second class, then post first class.
This gives people an extra day to pay, and I can then batch things up
better.
(speedevil, Wed 6 Apr 2011, 16:54, closed)