I recently left a well-paying, full-time job to return to school to work on a Master's degree. As a result, I have had to transition from purchasing whatever I want and going on expensive vacations to thinking more mindfully about what I am spending my money on. I created a spreadsheet with all of my expenses and my income, and realized the disparity right away! Now, I am no longer buying new clothes - I have a lot in the closet already and if I need/want something 'new', I purchase it from the thrift or consignment store at a fraction of the cost. When purchasing any non-necessity, I ask if I need it and if it's 'perfect'. If I feel 'meh' about the item, I don't purchase it, even if it's only $5. If I really like something, I put it on hold at the store, and if I am still thinking about it the next day, I try to consider pros/cons, and if it weighs favorably, I will go back to purchase it.
For my living expenses, I worked with the local utility company to change out the lightbulbs in my home to compact fluorescents (it was free!), and to install some simple insulation on the water heater pipes, which has saved me money on the electric bill. I also use the "GasBuddy" app to find the cheapest gas in the area when I fill up the tank and try to bike as much as possible. I save money on coffee by making my own at home (a French Press makes great-tasting coffee for a fraction of what you pay at a cafe), and I cook the majority of my meals at home, which I bring to work for lunch - saving me money, helping me eat healthier, and saving me time at school from not having to stand in line at the cafeteria.
I have also been going through my closet and garage to sell unwanted/unneeded/unused items on Craigslist and eBay, which has not only given me some extra cash, it has also helped me reduce clutter. When I graduate from school, I plan to travel around Europe via bicycle, staying in hostels, and the fewer items I have to get rid of then, the easier this will be.
I hope these ideas help out my fellow college students!