I know this is gonna sound kind of weird, but I find it helps to talk to myself whenever I prepare for an interview. Basically, I imagine what the interviewer is going to ask me, then I answer the question out loud.

The idea is this:
A lot of times, we have good ideas or we think we know what we're going to say, but then when we actually say them out loud, we realize that we could word them a lot better. So, by practicing what you're going to say, it helps you learn how to speak concisely, as a lot of us are prone to rambling. It also helps boost your confidence.

Best of luck!