A lot of people go off to college with no real idea of how to shop or cook for themselves, never having done it before. There are a few key concepts to keep in mind.
This isn't really a price thing, but it's still the most important for any cooking endeavor.
Food prep: Make sure your surfaces and utensils are clean. Make sure anything that touches raw meat or eggs gets cleaned thoroughly before it gets used with anything else. Especially anything that won't be cooked, like raw vegetables.
Food temps: Minimum safe cooking temps vary between protein sources, but for many animal based protein sources it's 165 degrees. Some things can be cooked to lower temperatures, and most protein sources have safety information on their packaging, but this is a general guideline. You'll need to invest in a cheap thermometer.
The easiest way to make even the cheapest meals taste good, is with a couple of seasonings. Even if all you use is black pepper and salt. Seasonings are one of the fundamentals of cheap cooking. Seriously. Black beans and rice make a delicious meal on their own with the right seasonings.
3: Stretching your protein source:
Protein is often the most expensive part of the meal, so learn to stretch it. Unless you're a serious athlete, you only need a couple of ounces per meal. So the best thing to do is to stretch your protein source as far as it can go. Rice, pasta, potatoes, and beans, are all good things to form the base of your meal with. Beans are the healthiest of those options, with potatoes ranking second. While you may think that many carbs is unhealthy, it's still healthier than eating in the cafeteria all the time.
4: Packing lunches/dinners:
If you don't live on campus, or won't have time between classes to head back to your dorm, make sure to pack lunches or dinners (depending on when you have classes). It doesn't take much effort to make the meals you cook a bit bigger so you can pack extra the next day. Once again, you'll have to invest in a small cooler, but it's worth it in the long run.
~ 3oz protein (eggs are usually the cheapest animal protein, followed by chicken.)
1 cup rice/pasta/potatoes/and or beans
½ cup vegetables (frozen is okay, but it can sometimes be even cheaper to buy fresh if you get what's in season in your area, and definitely better for you since frozen vegetable lose some of their nutrients.)
Seasonings suggestions: Basil, Curry powder, Garlic, Onion, Paprika, Parsley, Rosemary, Thyme, Chilly Peppers. There are also premixed spices if this list overwhelms you, but once you get used to using them, mixing your own spices is best, because you can get the exact flavor you want. (Parsley and Thyme have rather mild flavors, then there are Basil, which is slightly sweet, and Rosemary, which is one of the strongest herbs. Paprika and Chilly peppers will be your spicy flavors of course.)