Keep in mind that these are coming from a full-time student with no outside financial support. (As in, I've paid for everything since my plane ticket to the city where I go to university.)
I buy used clothes, and keep a lookout for clubs and whatnot at the university that are giving away t-shirts, and free dinners being had for various events, and never Ever buy my books at the bookstore. I've always gotten them from Amazon, half.com, or borrowed them from friends. Whenever I start to think I'd like to buy something, I figure out how many of hours at work it costs, and decide whether or not I'd be willing to work those hours again to have it. I don't buy snacks out of principle, unless it's really cheap and really tasty. Ramen costs 15 cents a packet, and can be supplemented with fresh veggies so you don't get that whole scurvy thing.
Jam it back in, in the dark.