If you already have a resume, I recommend calling and scheduling an appointment with one of the "professionals" rather than walking in like I originally did. They have students helping with walk-ins, and the "peer advisor" who sat down with me to look at my resume was totally clueless. He might have been able to help someone out who had never written a resume before, but he was really struggling with the questions I asked him.
After I realized the peer advisor wasn't going to be so helpful, I then scheduled a meeting with one of the professional advisors (Vic Snyder). For my meeting, I brought in a copy of my resume and told him exactly what field I wanted to go into when I graduated. He spent the next 50 minutes going over every miniscule detail of my resume with me and showed me how to highlight job related experience I never knew I had. Anyway, I thought my resume was good before, but it's so much better now. And I still plan on going back to have it edited one more time.
The Career Center charges once you graduate, so everyone who's graduating soon should get help while you're still a student and it's free.