1. BIG. This makes them easy to read from a long distance, which is important considering that the judges sit FAR back from the mat at Nationals.
2. LARGE LETTERS. Again, makes them easier to read. For color signs, you're best off ordering plain color signs (judges prefer signs to poms for a colors chant because hey are easier to read, but I recommend using both).
3. Held up sharply.
4. I agree with Gabrielle :p), stick to rectangular signs. I have never like circular signs, they feel too unconventional.
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For the cheer:
1. Limit the amount of clapping you do, doesn't earn you any extra points.
2. Don't have too much going on, stick to clean and simple (but difficult) stunts and tumbling or else you risk pushing the audience out of participant mode and into spectator mode.
3. The rhythm of your cheer should be catchy. Think of it as advertising.
4. BE AS SHARP AS IS HUMANELY POSSIBLE.
5. BE LOUD AND YELL IN SYNC WITH ONE ANOTHER.
6. Avoid forced ad-libbing/chatter. Only shout things like "yell it!" or "come on!" if the crowd isn't being loud enough, and do it with authentic energy. Don't force it, it sounds disingenuous and makes your team look performance-naive.
Great examples of sign/overall prop use: NLMS, Ravenwood HS, Westlake HS, Sachem North HS, Upper Darby HS.
Not so great examples:
-Bishop McCort (their mascot chant was perfect, catchy and easy to follow; however, their color chant was entirely reliant on poms, which aren't as easy to easy from a distance as signs)
-Greenup (again, name chant was perfect, but color chant forces the brains of the spectators to do two things at once: process pom colors, and and read and process the words 'GREEN' and 'GOLD', the signs for which were identical in color and design. Aim to only make the crowd process one type of information at a time. Also notice that during transitions, the girls voices died out a lot).
-Oak Ridge (as you might have figured out, I am huge on color chants being perfect. OR's 'RIDGE' spellout was everything it needed to be, but the color chant left a lot to be desired. When you have that many girls on the floor, it helps to have more signs, with larger, clearer words.)
Color chants are the EASIEST things to use to rack up points, because humans are built to understand colors before we understand words. Just look at babies.