I need some more advice to give to my sister on what she’s going to expect her first year of competing.(music, routines, costumes etc.)
Competing in what?
If it’s Freestyle unicycling, the best thing you can do, if you don’t have live riders around, is buy a video or two, and note the differences between winning performances and the ones that didn’t win.
Also make sure you’re familiar with the rules, so you know what the judges will be looking for. They are linked to the IUF and USA web sites:
www.unicycling.org/usa