Bounce your prepared interview answers off a wide variety of people you trust. This is not to get the perfect answer, but to get the impression you are giving off. I did this and I received some surprising reactions, sometimes contradicting opinions, all very informative.

As an example from myself, initially my answers were "too correct". If you tell someone what you think they want to hear, they pick up on that bullshit and they trust/respect you less. I then switched to more genuine answers, which has its own set of problems: sometimes people (mostly HR) actually do just want to hear the perfect answer, or they're judgmental and snobby about the genuine answer. However, at least I'm now actively deciding what impression I give.

Once you cut out the major errors in your interview answers, it just becomes a numbers game. After you interview with enough people, you'll just click with the right company.