When it comes to food, the more you can do your own meal prep the better off you will be. Pack and carry snacks. Drink Water! I cannot believe how much restaurants are charging for drinks! Avoid vending machines! (these are my weakness...)
On larger purchases, watch for sales, comparison shop, etc. Most importantly, learn to distinguish between "wants" and "needs." Smartphones range from $160 to $900. That's insane! Identify what features you need in a phone, and skip all the bells and whistles. Learn now to live not just within your means, but actually, below your means. Try to pay as you go as much as possible, rather than relying on loans. Stock up on school supplies during back to school sales.
Clothing: there are some nice second-hand stores. You'd be surprised at what you can find!
The suggestion to track your expenses is a good one. I recently started doing this, and have a detailed spreadsheet. I was surprised by how little I spend on "groceries" as compared to "household items"(bug spray, paper towels, etc), and "personal items" (toiletries, makeup, etc). Speaking of paper towels: rags are much cheaper (esp if you make your own!) and can be re-used sometimes. Some people go through a lot of paper towels!
If you want to learn frugal living, research things you can do with vinegar (glass cleaner, etc), peroxide (mouthwash), and other less expensive products. Household cleaners and toiletries are very expensive!
Take advantage of anything the school provides - entertainment, free printing in the computer labs, healthcare services, etc.
Your money management skills/habits that you develop now will carry into your adult life. Protect your credit rating. Pay your bills, on time. Lenders will look at this info when you try to buy a car or house.
It's great that you are seeking advice on this now. Best of luck to you!