The two main things you need to bring to tryouts are well-fitting cleats and a large water bottle.
Cleats. Most cleats that Ultimate players use are labeled as firm ground soccer cleats, but they still work for playing Ultimate. Not only do wearing cleats help to prevent injury, but wearing them will also improve your performance by allowing you to start sprinting and change directions quicker -- all things that help you lose your defender.
A good, cheap option for starter cleats is the Adidas Women's Goletto Soccer Shoe
A more expensive but more durable option is the Adidas Predator 19.3 FG Cleats
It’s important to make sure your cleats fit correctly, because bad cleats means foot pain after practice.
Water Bottles. Try to bring at least a 32 fl. oz (about 1 liter) bottle. Always remember to drink lots of water during your tryout.
Sunscreen. No matter the weather outside, you should always protect your skin from harmful UV rays.
Although the team will probably supply discs and jerseys for your first tryout, it is useful to bring these to future practices.
Discs. Here is a standard, official “game disc”. If you're looking to buy several discs, Discraft sells misprints of their discs that are functionally the same as any normal UltraStar, but are far cheaper.
Light and dark t-shirts. Coaches will sometimes ask you to bring a light (preferably white) shirt and a dark (preferably black) shirt to practices. They are used to help distinguish sides for practice scrimmages. Don't wear a gray shirt to practice/tryouts -- they're usually too indistinctly light or dark to work for use as jerseys.
The two basic throws of Ultimate Frisbee are the forehand (known as a flick) and backhand throws.
Practice your flick and backhand throws at least once before your tryout, especially if you’ve never thrown a disc before. You can practice throwing with a friend, family member, or even yourself. If throwing by yourself, aim for a target or a soccer goal to make it easier to pick up the disc afterwards.
Make sure you understand the basic Rules and Strategy of Ultimate -- when to call fouls, how to stall, and basic vertical and horizontal stack movement.
You can also watch film of Ultimate players to gain a better understanding of how strategies like vertical and horizontal stack work on a full field -- see links to these films on the Resources page.
You will likely never need this for local tryouts, but for the future, you might want to learn the set of international hand signals used at high-level Ultimate tournaments.
You're eventually going to want to fully understand the rules so that you can make accurate calls in-game -- so you might also want to check out the official USA Ultimate rulebook.
Lastly, and arguably the most important, is to take care of yourself before tryout day.
Sleep. Get your recommended 8-10 hours of sleep the night before. Studies show that the benefits of getting a full night’s rest include increased exercise performance and productivity.
Nutrition. Additionally, eat a large, nutritionally balanced meal before your tryout. You’ll need the energy to perform well at your tryout.
Teams are looking for players who display high endurance and speed, have consistent throws, and can communicate well with their teammates. Because of this, most tryouts consist of:
A warmup
Drills that provide players with the opportunity to display their skills -- these are usually different combinations of throwing/running/catching
This is where sprinting/change of direction tests come in, and where having cleats comes in handy
Scrimmaging, to gauge how well players work together -- these are in the form of 3v3 (minis), 5v5, or full-scale 7v7 games
Cooldown
Keep in mind that every team has a unique playing style, with emphasis on different skills required, so no two teams' tryouts will be exactly the same.
Another deciding factor in determining which players end up on a team's roster is how they interact with their fellow players. Teams will want to nurture a strong sense of community and sportsmanship, and the players that are openly friendly usually the ones that will thrive in that environment.
In some cases, displaying a strong will to improve and the ability to adapt to new situations will be valued more than the basic skills you might have, so remember to give tryouts your all while you're there.
Just remember: nobody there is perfect at Ultimate either -- and they were all once where you are at now. Don't worry if you're not able to perfectly execute all of the drills you come across. The coaches and the other players at tryouts are there to help you grow and become a better player -- they aren't expecting perfection from the get-go.
You can also think of tryouts as just a way to get a taste of Ultimate. Based on your tryout experience, you can decide whether or not you're interested in continuing playing.
Even if you don't make it on to the team, most teams still have open slots for practice players! Being a practice player means you still get the opportunity to play (and improve!) with the team in practices, even if you don't get to play during tournaments.
Hold the disc in your dominant hand so that the edge hits the middle of your palm and the face of the disc is towards you.
Finger placement: put your thumb over the grooves on the face of the disc. On the other side of the disc, your pointer finger should be curled over the rim of the disc, not resting along the rim. Your middle, ring, and pinky fingers should be pressed along the rim of the disc.
Without bending your elbow, bend your wrist so that the edge of the disc comes in towards your forearm. At the same time, swing your whole arm across your body.
When you’re ready to throw, quickly swing your arm forward while snapping your wrist forwards, and let go of the disc when your arm is perpendicular to the rest of your body.
Depending on how much snap and power you put behind the disc, it'll spin more or less and subsequently go farther or less far. Play around with the speed you release the disc, the angle you release it at, when you release it, and the amount of spin (amount you snap your wrist) in order to get the disc to consistently hit a target directly in front of you.
To see these steps in action, click on this video by Rowan McDonnell.
Use the doorknob trick and/or youtube how-to video to learn it.
A simple, 3-step explanation:
Pinch the disc. Make an "L" with your thumb and pointer/middle finger. Pinch the disc, with the rim of the disc in the crotch of your thumb and pointer finger. Make sure to grip tightly for more control in your throw.
Step out. Step with your non-pivot foot to the side. If you're throwing with your right hand, step out with your right foot (and vice-versa). A stable base makes a more stable throw.
Turn the doorknob/flick. Hold the disc parallel to the ground at shoulder height, as if you're holding a pizza. Move your wrist "opening a doorknob motion," while making sure to keep the disc level as it flings off your pointer/middle finger.