Hey Galen

All you need is your plane, some fuel, a way to get it started, your AMA card for registration, and the $$ required to enter, also a battery charger if staying overnight, and ensure all support equipment is charged also.

Now to help be more prepared
Make sure you have flown the sequence and if possible, are comfortable and maybe have the sequence memorized.
Go to the IMAC website and READ THE RULES, so you will understand the how and why for to the scores you'll receive.
Be prepared to ask the more experienced pilots lots of questions.
Make sure your plane has enough fuel to complete the sequence twice, with some extra flying time in the air.
Have or ask for a person to call for you, stand behind you and help you fly the sequence by letting you know what is next, and if warranted, give suggestions and encouragement.
I have gotten in the habit of always taking thin and med CA, 5 min Epoxy, spare servos, batteries, parts etc etc. If is will ever break it will be at a contest. Also through in a roll of the 3" clear packing tape(works wonders for lots of circumstances)

IMAC and Pattern is about having fun, meeting and making friends, and striving to fly better.

Have fun.

ed