Typically, the most popular choices for high school mascots are fierce animals or warriors. It's difficult to go wrong with these sorts of characters, and it's easy to find related outfits at costume retailers. Common animals include big cats, such as lions, cougars, bobcats, and panthers; canines like bulldogs, wolves, and coyotes; and birds, particularly cardinals, eagles, hawks, and owls. If you wish to have a more human mascot, consider pirates, Indians, cowboys, knights, and Greek or Roman warriors.
Typically, your high school will have two or three colors associated with it and its logo. Tying your mascot to these colors will ensure that is properly represents your school's spirit. Either choose an animal or symbol that normally shares your school's colors, or have your mascot wear a shirt or uniform that prominently displays your school's colors and logo. You can also incorporate your school colors into your mascot's name, such as the "Red Raider" or "Golden Sandstorm." In fact, having your school's colors associated with a mascot that is not normally that color is a way of making your school's symbol stand out for example, Duke's "Blue Devil."
Perhaps the best source for an idea that is distinctive to your school is the area in which you are located. Choosing a mascot that relates to the history and environment of your location will create a sense of loyalty among surrounding neighborhoods, and will give you an identity unique from other schools. One source for such ideas are local fauna; while plants typically don't make compelling mascots, choosing an animal that is native to your area (such as a specific breed of bird or horse) will convey a sense of community pride. You may also wish to consider the industry and history of your area; use your team mascot to honor a group of hardworking citizens (take the Pittsburgh Steelers and Green Bay Packers) or a historic figure that hails from your area, or notable alumnus of your school (Abington, PA's "Galloping Ghosts" drew their mascot from the nickname of a former running back.)
Who better to help pick out the mascot for the high school than the very students who attend it? Having your students help determine your mascot will create school spirit before your mascot even takes the field. First, have your students submit ideas for mascots. Narrow these down to five or six ideas, then have your students vote on the one that they would most like to see as their representative.