Invest in a Pick-A-Prof account. Do it with a few friends to spread out the cost. It's well worth it. Don't just look at the grade distribution though. Read the reviews (with a grain of salt) to see if a professor's style of teaching is similar to your style of learning.
Set a GPA goal for yourself each semester, in each class. Having a "carrot" in front of your face is a great way to stay motivated throughout the semester. I'm aiming for at least a 3.6 this semester.
For the love of God, use Academic Advising and Career Services! Keep in mind that the top internship programs have early application deadlines. Start thinking about what you want to do in the summer in the fall.
Keep your Facebook profiles clean and neat! Don't have "drinking" under your interests, sloppy make out pictures of yourself, etc. Your profile is accessible to everyone and reflects you and your sorority.
Don't avoid the library. It's a great place to study, you just have to find the right spot.
After rush is over and done with, don't bother waking up bright & early to look cute for classes. You don't need make-up, a blow out, etc. for your 8 or 9 AM class.
Credit cards: only have one. Pay off your balance every month. Do not graduate with c/c debt and a bad credit rating... you'll be screwed. For purchases under $10, pay in cash ONLY.
MAJOR IN SOMETHING YOU LOVE. Your GPA will thank you. Concentrate on a high GPA, a great resume and good internships. It will get you and interview where you can really sell yourself. So many people in hiring have told me this. Also, don't feel like you have to major in political science to work in D.C. or in biology for med. school. DO WHAT YOU LOVE!!