Pick a person that you know to use as a map for your character, or a celebrity might also work for this idea. Make some changes in your character such as changing the hair color or adding a super power. You do not want to have your character exactly like someone in your life or you may end up offending her. This will help your character look like a "real person" who is well-rounded.
Choose a place for your character to live. The country and city that your character lives in will determine a lot of factors about who that character is and how her culture shapes her. Choose what sort of living conditions your character has. Does she live in a shack or a mansion? Determine whether your character lives by herself or if she lives with family members or roommates. Ask yourself why your character lives where she does.
Choose a background for your character. Imagine how your character grew up. Choose the type of family your character had as a child, or if she grew up in an orphanage or even the woods. If your character came from an abusive home or lived with a single mother, these factors will influence her emotionally and how she views the world around her.
Choose how old you character is and what she looks like. Age will affect the personality of your character as all generations view the world in a different way. Give your character a physical description that is both interesting and realistic. Your main character may be blonde with beautiful blue eyes but three hundred pounds overweight. This will have a large effect on you character's world view.
Record all of your dreams in a journal. Dreams contain vivid and interesting characters with unusual characteristics. You can use the whole character that you see in a dream or just get a few details from her that you can add to another character. Dreams come from our subconscious fears or feelings, and the characters in our dreams that result from these feelings will often have the same effect on our readers.