Anime girls grow fangs when they're mad. If you fall in love with a girl make sure she IS a girl first. If you're trying to defeat a Dark Lord, throwing a spell named after them is really dumb. Never EVER try to sleep when a redhead is talking to you. The ones who look the friendliest are the most likely to single-handedly wipe out most of a species.
Girls are deadly.
Do not get in our way. Sometimes the best weapon is an ear-piercing laugh. If you want to look mysterious, good lighting, sound effects, and eerie music will do the trick. Clanging a staff is also a nice touch. And hope they last.