One of my favorite resources for fleshing out a character is the vast wealth of portraiture found online. Art, photos… There are multiple ways to use such items to help you with a character. The two major ones are art to character, or character to art to character.
Art to character: In this case, you simply find a portrait that inspires you and create a character around it. Your character doesn’t have to ‘accurately’ reflect the portrait: for example, you might base a female character in a fantasy world around a painting of fairie queen, even though your character is wholly human. The important part is that some element of the image fires your imagination and helps to fill out any gaps in the character you’re creating. Clothing, hair, facial expression, body posture, gesture: all of these things can inspire character elements.
Character to art to character: In this case, you start with a character you’ve already begun. You then look for an image that suits that character. This can take quite some time (particularly with male characters—it tends to be much more difficult to find male portraiture), but can be very worthwhile. You might end up picking out one or more characters that are close to what you want but off in one or more details. Then, you reverse it: you see what additional inspiration you can take from any image(s) you’ve found, just as in the first option.
I created a DeviantArt account largely so that I could start collecting DA character portraiture in a convenient place. It occurred to me this morning that I should link to that collection so that anyone who comes across this might use it as well. So here you are: the ever-expanding collection of character images. Here’s one of my favorites:
Mystery Guest by ~Niquita on deviantART