My gym puts a video of a parent doing the hair on their kid so less experienced parents know exactly how to do it and can do it while they are watching the video and pause it when they need too. We do the same for makeup, and typically only do one eye because it can take a while.
As for what the gym I cheered at does (i now coach at a much smaller gym, not the big name I used to be at)....
HAIR
Minis- High Ponytail or Halfups for kids who don't have enough hair to put it in a ponytail
Youth 1-4, Junior 1-4, Senior 2-3-Straighten High Pony Tail with a poof, half ups for kids who don't have enough hair
Junior 5, Senior 4-5- Poof w/ bow, hair down in crazy curls, most girls just wear curlers the night before, you can never rely on a curling iron....
MAKEUP
Minis-Natural Face, Red Lips (coaches do this with just red lip gloss right before they go on), White eye shimmer, mascara
Youth 1-4, Junior 1-4- Natural Face, Red Lips (the kids/moms do this with lipstick and lip liner), white eye shimmer, eyeliner on the top, mascara
Junior 5, Senior 2-5- Anything we want, but when the coaches say that they really mean something pretty, no crazy colors. i always do red lips, natural face but with some bronzer, black eyeliner on the lid and waterline, brown eye shimmer, TONS OF MASCARA
hope this helps, i think they did a good job of keeping everything age appropriate and not to crazy, and everyone looked gorgeous because its so universal and works on most faces!