For your own experiences, and especially if the fraternity you are pursuing is known for their extra-curricular activities (on fraternity at my school was knee-deep in Student Government, orientation, student tours, the newspaper, etc.), by all means join a club or two.
Besides it "looking good on your resume", you will be able to learn and experience something new, become involved and care about something, and perhaps gain leadership positions. All positive stuff from every perspective. It also gives you a chance to see how you balance grades and something else.
Give them a reason to want you to be part of their group; right now all they might see is someone with good grades. You may end up meeting people in the Greek system and finding things in common with them. Don't become friends with fraternity members just because you want to pledge.
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