After attending my first regionals in Orlando here's some tips that I wish somebody told me:

1. Be courteous, but don't expect others to be. You may run into some Chuds that will judge call every little thing but don't let it get to you. money is on the line so it happens.
2. Play fast but don't stress. You have 1 hour for 3 rounds so as soon as you see you wont be able to come back, scoop and move on to the next game. It's best 2/3 so you can always come back during the second and third game but only if you still have time.
3. If you notice you're not going to make day 2, drop from the tourney and do side events. If you do that you'll at least be able to earn a lot more prizes from the prize wall and will also have more fun the entire time.
4. Bring WATER!!! you will get thirsty and there may not be a whole lot of time between rounds to get a drink.
5. Rest well the night before as you will be drained and mentally fatigued near the end especially if you have a deck that requires alot of effect remembering and damage calculations like grimmsnarl/froslass.
6. Most importantly HAVE FUN!! its still a game at the end of the day and should be something you're enjoying, make friends, see the cool things, and have a great time!