In the eye of the beholder

Write about your character (can be the main character, villain, a minor character you're intrigued by) or a favorite character, or a character from a favorite book, from the point of view of a stranger. Put the character in his or her element or everyday life and describe someone's first impression of them.

Pay particular attention to the character's flaws and weaknesses. They're often more intriguing than their strengths and what the reader will watch them struggle to overcome as they strive for their goal.

If the character is the opposition, pay attention to their strengths. These are what they'll use to oppose your main character.

Now try putting the character in a situation they don't feel comfortable in. Now how would a stranger describe them?