Golden rules so you don't loose all your marbles, (well I have not quite lost them all yet, although a glance at the Lounge might make you think otherwise )
1) Write listing content off line for pasting later
2) Upload all images for a set of listings
3) paste in description
4) select in images
5) preview
6) error check
7) SAVE (sorry to shout but very very important)
8) repeat 3 to 7 for remaining listings of set
9) schedule the set
10) take a breather while the listings run and the cash rolls in