As a student, professors and staff on campus might be the best indication of your work ethic and experience. Get to know your professors and the staff on campus, whether this be through classroom or program experiences. It's their job to give references for students—just make sure you ask first.
Your academic or career advisor probably has a good idea of who you are, especially if you keep in frequent contact with them. As with faculty and staff, most advisors are willing to serve as a reference if asked.
Coworkers and supervisors at current or previous jobs—as well as long-term volunteer experiences—can speak to your work. These are great references! Remember to ask permission before listing them as a reference. In addition, keep them updated on what positions you are applying for to avoid surprises when they get emails or phone calls.
Use extreme caution on selecting "other"—just because it's an option doesn't mean you should choose it. If you have a strong professional reference that doesn't quite fit in the other categories, put it here. This does not mean your family, friends, or religious leaders (unless you worked directly for one, then list that under coworker/supervisor).
You might be tempted to list high school teachers or other references from high school. These aren't the best references now that you are in college. We understand some of you are freshmen and have had limited time to develop a connection with the IUPUI community. Many first-year professors and advisors are happy to serve as a reference for now. You can replace them later as you grow your network.