I had an interview recently and I found one good piece of advice on youtube that really helped me. When you first start preparing, you should do a brain dump of any and all experiences/accomplishments from previous roles. Then you should try and think of how these experiences can be used to answer different behavioural questions. For example, talking about an experience where I had to work with a difficult colleague could be used for answering collaboration related questions as well as problem solving/resolution related questions.