The most overlooked aspect of Ultimate is the importance of a strong mental game. In particular, Ultimate at the elite level becomes a game of the mind and not one of athleticism. A strong mental game is what seperates the super talented player who can't perform at tournaments from the mediocre player who plays consistently at practices and tourneys. It's also what seperates the top elite teams from the rest, past UPA champions have had to learn from their losses before they took home the trophy.
If you want to reach a goal, you have to know what the goal is, and to be able to see it being done. It's similar to the way that a player molds their style from players that they play with. The reason that you slowly throw like players you respect is because you begin to visualize how they do it, and one way or another this translates to you yourself doing the same thing.
Visualization is a concept that is straightforward, but requires real practice and dicispline to use effectively. In short, you should be seeing yourself from all angles (3rd perspective, 1st person) catching the disc, making the big plays, skying your opponent. Everyone will have their own way of visualizing situations, but either way, it's more important to not visualize mistakes. A classic example of poor visualization is the handler who is going to catch the pull and has a hundred thoughts running through their mind as they are about to catch the floating pull on double game point.
Pregame routines are useful to develop if you want to reduce the uneasiness that comes from playing in tournaments. By doing the same pre jog, stretch, and drill at practices, the mindset of the players will be more game ready come tournament time.
Some teams like to stretch in a circle, and sometimes in unison. Although stretching is highly advised, stretching in sync is probably less effective than if every player does their own stretch... not every play will have groin problems, sensitive knees, or recovering ACL's.
Another part of the game that seperates the experienced teams from the rest is the sideline presence or eight person. At no time should your teammates be conversing among themselves about their social situations, or making jokes about that player who runs funny. Instead, your teammates who are not playing should line themselves spread across the sidelines (on both sides) helping your teammates who are on the field. It takes practice to yell the appropriate things, but the best approach is to single out one player you want to help, and to tell them things you think would help yourself had you been playing.
Although the list of things you can yell to your teammates is endless, here are some of the most common and important ones.