I was asked by the school to tutor, which pays miserably few hours but is a nice little bonus at the end of the semester and works into my own studying nicely. I also got hired as an overnight ICU tech in the large animal hospital this spring, so I've started that - it's only one or two nights a month, about 8 hours each time. Miserable wages, but excellent experience and flexible enough to work around when we have exams and things. I also make a little extra when I can giving riding lessons and riding a training horse or two.
Basically I make enough to buy some groceries and supplement the help I get from my family. Other people tech at their home clinics on weekends, or are on-call in the diagnostic lab or Idexx for necropsies, bloodwork, whatever. We also have a student ambassador program - they get paid to give tours and work Open House and other events, and it's apparently a pretty good gig. I also have a classmate that's kept her waitressing job one or two nights a week - no idea how she manages that. I depend on making money in the summer and on help from my family to pay for my living expenses. Honestly I don't think there's any way to make enough to put a dent in your loans.