Unfortunately, it can be very difficult to cut your basic expenses: shelter, cost to commute (including gas, maintenance, permits, etc.), utilities (water, gas, electricity, only), food (excluding incidentals: morning coffee, random snack purchased at the coffee stand). However, it is not necessarily impossible.
Cost of Shelter: Get roommates…if you are a grad student or even a post-doc you will probably rarely see them anyway since you’ll be in the lab all the time. Move back home (if you have willing family in town), remember not to take them for granted and pay for your own food, use of utilities, or help out whenever you are actually home.
Cost to commute: join/form a vanpool or a carpool if you live far away. You can split the cost of gas and parking. If you pretty much live in your lab, look for others with similar schedules that live in your geographic direction. Determine if the cost of transportation negates any monies saved by living that particular distance from school. If it does, consider moving closer. If you have reliable public transit, see if your school offers discounts and take advantage of them. Remember, the true cost of vehicle ownership includes: Insurance (don’t just write it off even if you’re on someone else’s plan, also regularly check to ensure you are getting the lowest rate relative to the coverage you need), License/Registration fees, gas/oil (don’t leave the car empty if you’re driving someone else’s car), parking permits (these can add up), maintenance (oil change, repair costs, etc.)
Cost of utilities: If it’s not bundled with your apartment, you can save here as well. Save water. Learn to take 2-min showers, because as a grad student, you need all the spare time you can muster for sleep. Alternatively, if you have a membership at the university gym, shower there. Electricity/Gas: Turn off the thermostat. You will be in the lab all day anyway (and hopefully it’s reasonably climate controlled).
Cost of food: For cheap produce, try the small/international grocers. Form a wholesale circle (get a few friends together who will split the cost and loot from your wholesale membership. Buying bulk is cheaper, but only if you can actually use everything up.) Make use of your freezer, since sales come and go. Meat is expensive. Keep to small portions of meet and make up your protein with a variety of beans. I’ll cover food-savings in detail later.
It is a spartan regiment to follow, but you can save a lot. Of course, it’s best to pick and choose what you can live with rather than make yourself miserable. Especially since these are the basics! There are still lots of other places to save, so make sure you’re comfortable but not wasteful.