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.
Same. If the author spends an inordinate amount of time describing a specific feature or look, I sometimes take a step back and try to imagine the character in detail, but I can’t “retain” that image for long in my head - the character goes back to being sort of amorphous.