I've been through a few successful promotional processes in LE, so at least adjacent. I always suggest figuring out the questions you believe will be asked, if its anything like law enforcement some version of the same questions appear on most tests. Crafft your answers that are true to you and do a good job selling yourself for each one. Write the questions on a note card and then put the main bullet points on the back. Put them on the kitchen counter and have the folks at home randomly grab one and ask you.
This helps with a few things. You aren't trying to remember a verbatim answer thanks to just having bullet points, so the answers change a bit each time and feel more natural. Also, if you are like me, in the moment you'll still get nervous and going over them, out loud, to someone else at least helps with the prep so you'll forget less things. In the testing processes I've helped with it is always apparent who is saying these answers out loud for the first time.