I currently work in Student Affairs and the biggest piece of advice I've been given about pursuing a career in this field is NETWORKING is crucial! Definitely get involved on your campus, get to know people and what they do, what dept/office they're affliated with, and maybe sit down and talk with them about how they got to where they are now. That's how I'm getting to know quite a few people on campus. And you'd be surprised how willing people are to connect you with other folks in the field!
If you want your fingers to do the walking, look into joining NASPA (http://www.naspa.org/) and the Placement Exchange (http://www.theplacementexchange.org/).