We have primary resources: those things we know. They always say write what you know. We have memories and experiences, and second-hand resources of others – diaries, interviews and people who knew them.
Secondly, we can seek experiences. Ask to be locked in police cell for a few hours. Learn to sail. Take a trip around a racing track.
Thirdly we can explore with our imagination. Of course, even that is based on our own experiences. But we really do need this resource if we are to write fantasy and science fiction. Even using our imagination is working with what we know. We see the scenes and still write with our senses. They relate to what we have already experienced.