As @jldugger said, shop around for textbooks. Make sure to look for used books: you can sometimes save a lot of money there.
Be smart about food money. I could go to our on-campus grill and get a sandwich and a salad for lunch. If I packed both with toppings, the salad could be a 2nd meal for the same day. If you have the option, get a meal plan that is just 1 meal a day, and eat a lot that meal.
Don't do the starbucks "pay several dollars for a coffee each day" thing. Small-ish regular expenses add up quickly.
Quit smoking (if applicable).
Ditch your car if possible. Some colleges are in cities with good public transportation or are small enough that a bike will do. Cars are very expensive.
Try to find free activities to do in your free time. Usually college towns are great places to find free fun. Pick-up sports, student concerts/art shows, playing board/card/video games.
Make sure to track how you're spending money to look for areas where you could be spending less. There are plenty of tools available to help with this.
Some on-campus jobs involve sitting around and occasionally doing something: IE working the checkout desk at the library. A job like this (if you can find one) can effectively pay you for doing our homework.
One other very important college-related financial tip is to not take out more loans than you can afford. I've heard a good rule of thumb is not take our more loans than you expect to earn your first year after graduating. Look up average starting salaries for the career you realistically expect to have after you graduate. If you would need to borrow much more than that to get your degree, rethink your plans. Being a slave to a bank for years is a crappy way to spend your life.