In the old days, before the internet and CDs, there was a band called "Styx". A member of Styx, a man named Tommy Shaw, was interviewed on television. During the interview, a fan recognized Mr. Shaw and politely asked for his autograph. Shaw was happy to provide it.
While signing her autograph, the fan chatted with the celeb about her music and how she likes certain aspects of it, before asking her about upcoming projects. After chatting for about three minutes, the fan thanked Mr. Shaw for his time and walked away.
Shaw returned to his interview and marveled at the size of the fanbase. I was very impressed.
When talking to a famous person, it's best to express your appreciation for their work and not talk about the past, but ask about future projects they're working on.