The worst is when you prepare a conversation in your head but then when you have it in real life, people ask all the wrong questions and now you don't have the proper answer prepared. So better attempt to predict every single possible way the conversation could go, that'll surely help and not just bog my brain down to the point where I don't get anything done!
I had a particularly lengthy interview of myself by myself recently on the toxicity of the enormous amounts of corporate greed our society is experiencing and how its driving the cost of rent and other neccessities up, essentially pricing people out of existing, I would suggest you watch it but....well
For me, my expertise would center around one or two interests at one time, depending on the context: music, writing, architecture, history, visual arts, and most of all, fan fiction.
Had a pretty good interview with myself an hour ago when I was asking me how to improve health care by offloading technical procedures to nurses rather than having them done by doctors. I agreed with myself that e.g. taking blood samples is better done by nurses who are really good at it, how it's not just a skill but an art, and how having really proficient nurses would increase their overall job satisfaction, would lead to higher quality health care in general, lead to lower costs and better patient outcomes. I agreed!