How to prepare for behavioral interview?

Preparing for this round is one task: build a small set of stories before anyone asks you for them.

Most candidates prepare by reading example questions. That produces recognition, not readiness. When the question arrives you still have to search your memory under pressure. The first story that comes to mind is usually not your best one.

Six or seven stories cover almost everything

There are about nine question categories, but you do not need nine stories. A good story answers three or four different questions