Being yourself on the interview is not part of the game. Only in rare situation somebody will appreciate your honesty and you could discuss your experience and potential job without having to pretend. Most of the HR personnel and interviewers will say that honesty is what they want, but that is simply not true. They want you to be honest so they could discard you as a potential employee. That is why you have to fake it.
1) Never say you are there because you need money
All of us are looking for a job because we need money. But don't say it out loud. If you say at your interview: "I am here because job is well paid and benefits are great", you are making a great mistake. You are there because you like the job, it is your dream job and you are the perfect candidate. Money is not an issue at all. You are prepared to work overtime without vacation because you absolutely adore that job.
2) You need to look excited for the job or the company
In all job search advice websites you can find that what employers like to see is enthusiasm for the job or company. If you have it that is great, but if you don't you need to fake it. Practice it at home, prepare sentences in your head. Say something like: "I was so excited when I heard about this position." or "I am following your company for some time." or "This is a dream place to be".
3) Prepare answers in advance
Some interview questions are overused. For example famous questions like: "Where do you see yourself in 10 years?", "What is your greatest weakness?" etc... There are plenty of books, courses, and advice on how to answer them. Nobody is expecting honesty, not even interviewers. If you try to be honest, and think about the answer on the spot, you could look like somebody who comes unprepared and doesn't know to google "most common interview questions". It certainly doesn't look good to make an impression that you don't prepare for obvious things. There is a pattern on how you should reply some of the questions, and you need to follow it.
4) If competition is doing it, you have to follow
Let's be honest. If you don't fake the interview, other job applicants will. Consequently, you will be at disadvantage. Don't let it happen, be prepared.