I got rejected from many behavioral interviews. In a similar vein, the main thing that helped me was the realization that I had to work on my personality as a whole and then the interviews automatically got better. Especially making projects that showed that I cared about contemporary issues was a big plus.

In general: you want to be very humble and appreciative but also enthusiastic about the role. Try to talk about a project/hobby that intersects with the work they do. Try to start off average but once they get to know you, you want to be more friendly/likable (don’t give it your all from the start, it might make you look desperate). Also sometimes it’s not your behavior & there’s nothing you can do but to find another role. In my experience I always found a better job when I was looking for longer so it’s all good.