Reduce the use of single-use items and invest in reusables; water bottles, silverware, bags, etc.
Avoid using products with excessive packaging. If possible, shop locally and support your neighborhood! (Swapping out fast fashion for second-hand shops included!)
Reduce mindless consumption of animal products. For example, consider adopting Meatless Mondays.
Compost! If you live on or off campus, there are several compost drop-off centers nearby! Union Square Farmers Market, Tompkins Square Park, etc.
Reduce electricity and water consumption! Remember to switch off the lights when leaving a room and limit showers to under 10 minutes! When possible, install a low-flow showerhead and switch to fluorescent light bulbs.