Series structure

Katherine asked: Could  you please share your thoughts on shaping a good story / balancing the form, particularly across a series?

If you are setting out to commit a series on purpose, with malice aforethought, the first few things you need to think about are: 1) Do you really want to do this? 2) Do you actually have enough material for multiple books? And 3) Do you have the personal commitment and stamina to write multiple books about the same place/characters/plot/theme/idea without getting...