Most of the time I do nothing to prepare, except maybe wear a nicer shirt. There are some exceptionally few rare times I do some research on the prospective employer.
I absolutely do not cram some information about a technology which I have not used prior. I just don’t know it and leave it at that.
If you want to be awesome at interviewing then speak with confidence, answer only the questions that were asked, be honest. It’s really that simple, but the actual preparation takes years of reality.
There are three things that comprise high confidence. The first is strong social intelligence. That means listening to people: verbal, vocal, and physical. Take it all in and respond appropriately. Second is actual real world technical experience doing the work asked about. Mastery of a craft results in emotional comfort when discussing interconnection between deep moving parts. Third is strong communication skills, which is a mastery of expression, especially speech. Strong speaking skills allow precise conveyance of a subject’s technical minutiae without pause, stutter, or repetition. It also allows for strong persuasive dialogue.
Good confident interviewers are looking for the fakers: liars, pretenders, and narcissists. These are people, for whatever reason, struggle and fold in the face of brutal honesty. Weak interviewers, people who lack confidence or exhibit low self esteem, are more likely fooled by fakers. The primary goal of a faker is selling their own fragile ego, the amazing snowflake unicorn gift to the world that only exists in their own mind. Converse that to a high confidence person whose goal is some form of product creation, because it’s not about them or their ego but the thing that gets delivered, which they have done multiple times in the past.
You cannot just prep your confidence before an interview. You have years of experience with some collection of skills and talking with people or you don’t. Fakers will try to convince people otherwise, and some people are easily charmed by their foolishness.