I don’t always have an image in my head of a character right away. Sometimes, they are more a collection of features built around a very vivid personality. A friend of mine, who is a writer, prints out inspiration for her characters and pins them to a board. Then, when the story is written, she has a tradition of taking the pictures down and putting them away to make room for her new characters.
I haven’t had a printer in a few years, but I do have a Pintrest board. I don’t always have characters there (I usually do), but I may have the setting, or historically accurate costumes. In one character’s case, I used Roman busts as inspiration.
Check out a few of my boards below.