In those tedious TV makeover shows where they redesign some poor sods house, they tend to ask the people to put together a collection of imagery that they like the look of, to serve as inspiration for the designers. I always thought it was a bit arty and poncy, but I've started doing the same thing for my games.
My new game is based on the music business, so I've started collecting a pile of images on those lines, to inspire the visual design for the game. Pictures of guitars and amps, of gold records and mixing desks, famous rock stars etc etc. I changed my windows desktop to be an album cover from a band I like, and have been listening to classic rock in the car and while I work.
I'm lucky in the respect that I play guitar and used to work as a guitar teacher and occasional live / session muso, so I'm fairly familiar with how it all works etc.
I think that people making games, or TV programs, movies, or writing books should absolutely surround themselves with the imagery of what it is they are making. If you are working on a WW2 FPS, your office *should* be as full of WW2 stuff as you can make it. If your doing a city building sim, fill your office with architectural drawings and posters of city skylines.
I'm going to have to dig out my bullet belt and leather trousers.