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.
Most of the times I picture the character as If I could only see their back. I see thier outfit, complexion, hair, even I can imagine their voice, the way they move and the way they smell (if it’s well written). But I’m unable of imagining a face, if it’s described in the book I can only picture the parts of the face separately.
I don’t picture them at all. If the author gives a descriptor multiple times then I generally keep that in my imagination because there must be a reason for stating it more than once. I’m part of the no visualization crew so I don’t really bother myself with details that aren’t given. Characters, to the extent that they exist in my mind, are made up of their actions, thoughts, and situations, very rarely are they given a face.
Mostly by the cover. Or some other semi-official pre-made art (like I think the Hobbit characters looking like how they pictured in certain comic book). . Some authors describe their characters in clear detail so I just know how they look. Sometimes I compare them to similar characters and think that they look quite the same.
The books I love most are those that bring me into the lives of the characters. And I am open to picturing the characters the way the author describes them. That’s what I love - to be drawn into another world and the stories and people from that world.
I usually think of them as naked people