I find it interesting that Yankees who may beat on the South for everything from accents to hairstyles to ancient history are so intimidated by Greek recruitment.
Be your usual self, but polish it up. Mind your manners - VERY important, especially around the ladies. If you don't know much about manners, get a book and learn.
Don't make ignorant statements such as "Back home we did it this way" or "Why is everything so redneck here" or "Where are all the bagel places" or "Why does this town only have 3 Catholic churches?" Think before you open your mouth (good advice for anybody from anywhere).
Be friendly, and LISTEN to people. Smile often.
A couple of things to remember - saying "Sir" and "Ma'm" is looked on favorably around here, not so much by people of your own age but by anybody older. You might, however, want to use it at first with girls.
The term "Yankee" does not mean we think you are a fan of the Pinstripers. A Yankee is someone not from the South. Doesn't matter that they're from Oregon or North Dakota or Ohio or Maine. You're a Yankee if you're not from the South.
But don't worry too much. Almost any manner of social blunder can covered with the remark, "What do you think of the football team's chances this fall?"