Students still in school should be thinking about building their resumes now, so that when they graduate and need a job, they aren't starting from nothing. I receive all too many resumes from recent grads who have literally no work experience: nothing, not internships, not temp jobs, nothing at all. And since they're competing against candidates who do have experience, they're at an enormous disadvantage.
The most useful thing students can do to prepare for the job market is to work. Work before you actually have to work. It's the single best thing you can do to make yourself marketable.
No amount of fancy resume writing will disguise a lack of work experience. Your great extracurriculars and relevant coursework and summer abroad, while surely engrossing to you, do not give hiring managers any confidence that you know how to work in an office. Because here's the thing: There's a learning curve when you enter the working world. It doesn't matter how much you studied or how fantastic your thesis was--you don't yet know how the work world works, and you only learn by joining it. Anyone who has spent time working has a leg up on you in that regard.
So, find a way to get actual work experience before you leave school. Do internships every semester you are able, so that you have experience on your resume. Paid, unpaid, whatever it takes. If a part-time job of a few hours a week is all you have time for outside of your classes, that's fine. Do that. No one will hire you? Find work experience as a volunteer--that counts too.
Do something so you can provide evidence that you've spent time in a work environment, because that means that you're going to be further along the learning curve than those of your peers who haven't. And that means that I'll get to spend less time explaining office basics to you and you'll spend more time being productive.
Alison Green is the author of Managing to Change the World: The Nonprofit Leader's Guide to Getting Results. She is chief of staff for the Marijuana Policy Project, a nonprofit lobbying organization, where she oversees day-to-day management of the staff as well as hiring, firing, and staff development. Her writings have been published in the Washington Post, the New York Times, Maxim, and dozens of other newspapers. She blogs at Ask a Manager.