One of the biggest issues I've seen with my friends and heard anecdotally through out my time in school is lack of financing. It even affected me my first year at Northern and was the factors to my lack of success.
Many students have student loans, a new found sense of freedom and an innate ability to find high interest bearing credit cards.
At the beginning of every semester, sit down and fill out a quick budget sheet (I actually recommend making a more detailed budget, but first things first) to figure out the minimum required for you to survive per month. Include things like rent (if you're not in the dorms), fraternity dues if you plan on rushing and about $200 per month for food if you don't have a meal plan.
I recommend you use this
to create your budget, its easy to delete and add expense and income rows if you are a little handy with Excel.
From here, you can begin toying around with how much you have to play while you are in school.
Allow yourself ample funds to go and play; enough (if you're of age) to go have a drink at the bar or catch a movie with the guy or girl you've been making eyes at in your Biology lecture.
If you're really up for it, put your student loan money into an on-line checking/savings account such as ING Direct (they offer both savings and checking accounts at 4.04% currently) or HSBC. If you have three thousand dollars sitting in there, you'll be making about $30 a month in interest. After one semester, you're up about $150! You can use that as discretionary money, or to pay off your loans.
