To earn points (albeit slowly) sign up for e-rewards.com (various) and e-miles.com (Delta SkyMiles). You take surveys or watch videos and earn points.

Another trick with limited spending would be gift card churn--I imagine a college student should have no trouble putting a Starbucks gift card to good use. Find areas you get percent of point bonuses like grocery, gas, office supplies and churn cards from those locations.

If you have a flexible schedule you can watch the deals sections and fly cheap flights to unremarkable places like Omaha or Buffalo for cheap and possible rack up enough segments for elite status. As a student I used to interview at places I wanted to visit to get a free trip--interview in Burbank and visit LA, interview in Stamford to visit NYC, etc.

And also, never hurts to ask parents, relatives to donate miles to you.