Personally I give each character a face, either from a person I know who matches their personality or a celebrity that fits the description, even though sometimes it can be really annoying if the author gives more details on the persons appearance and my character doesn’t fit that lol. I’m very curious as to what other people do.
I do the same. Once I start to get a feel for the character, I start to see them more clearly in my head. If it’s a character that hasn’t made me feel anything towards them, they remain blurry. Sometimes I get either disappointed or pleasantly surprised when there’s a movie or tv adaptation.