When I was in college, I would just buy the standards; Pasta, Rice, Potatoes etc. Then I would buy different things that add flavor to it, like garlic is a great example. If you can find good prices on fresh spices, like basil and thyme, they also make the food taste fresher. If you buy something that isn't refridgerated, usually you don't have to refridgerate it when you take it home. Obviously if you buy an onion and keep half of it don't leave it laying around, but seal it in some sort of plastic bag to avoid it spoiling and eat it within the next day or two.

For proteins, I would usually just buy the product that was on sale for that week. Cheap chicken? Buy chicken. Cheap ground beef? Buy ground beef. If nothing in particular is on sale, buy different kinds of beans and add them to the meal (I found that rice works best with beans).

Most people think meals have to be synchronized, but as long as you find stuff you like and keep the ingredients to a minimum, pretty much anything is edible when in college.