I think rent and food usually take up the largest chunk of a person's paycheck. Rent costs usually can't be changed so food is the first thing most people focus on. Value meals at fast food restaurants are what many would resort to. There are recent health trends which claim fasting 16-18+ hours a day can have a healing/regenerative effect on a person's body. Fasting can also help reduce cost per day spent on food and have health benefits as well. There are a lot of little things a person could do to save money on food. Buying a 5 gallon jug and filling it with potable water at supremarkets rather than buying starbucks coffee or something else. I think they charge around 50 cents for more than a gallon of drinking water which is much cheaper than 50 cents for 12 fluid ounces of what you'd get in a can of soda.

Cost savings extend to entertainment. Doing things for fun that don't require money to be spent. I never took any of this seriously but I did save near to $10,000 inside 2-3 years, once. Just by being a boring person, not going out all the time, with my main source of entertainment being hanging out at a skatepark trying to learn new tricks on a skateboard.