Write the best resume you can and continue to add to it not only through your college years, but also throughout your career. The resume is a living, growing document that is always being improved upon. (NOTE: Please write your own resume! This process is important to your interview preparation.)
If you don't have a resume, write your first draft with help from Career Services and/or the plentiful information available on the internet. The Career Services Guide is also an excellent resource (including examples) that is available to you free of charge from Career Services. Many resources are also available from the Career Resource Center (CLB 235).
As was mentioned above, type "resume writing" into a search engine and you will also get lots of information on this topic. (Another NOTE: It isn't necessary to pay for resume help. Many sites offer free information not to mention the help available on campus.)
Once you have your first draft together, be sure to have it critiqued by several people. Career Services has a walk-up window where you can get another person's opinion. The OM&IS advisor will also be glad to provide constructive criticism.
Another way to get started on a resume is to enjoy a cup of coffee and devote an evening to browsing the many, many resume books in your nearest bookstore. The bottom line is, if you haven't got a resume you need to put writing a resume at the top of your "to do" list.