There is a lot of bad information out there on how to prepare for an interview, much of which is actually counterproductive to the process. Please DO NOT go out on Google, search for sample interview questions about behavioral interviews or any other type of interview process and waste your time writing out and memorizing answers to these questions.
The result is likely to be disaster. First, you have no idea what type of questions the interviewer will ask. Even if you hear from someone who has interviewed there before that Company X uses behavioral interview techniques, you do not really know if they do or just the person they interviewed with did. Additionally, no matter what methodology a company uses there are always multiple high ranking employees who can’t be bothered to learn the process and therefore interview the same way they always have.
So now your friend told you to prepare for behavioral based questions and you spend hours doing so and you go in and the very first interviewer asks none of the questions you have painstakingly memorized questions for. First you get a little nervous, second your confidence goes downhill and next you are fumbling for answers to even the most basic questions. You just lost the opportunity to work for this company.
Worse is you go in and they ask you exactly the questions you are expecting and you answer them all based on the memorization game you played with yourself. You leave the interview feeling great and you never hear from that company again. You have been rejected and they never even bothered to call and let you know, let alone let you know why.
In this case the reason you were rejected was your answers sounded rehearsed and therefore fake. Best case scenario is you lacked credibility, worst case scenario they just flat out did not believe you. When you interview you are competing and when you compete with others of similar skills and background, it is individual most prepared who will win. How are you separating yourself from the competition?