Start calculating the cost of each dish and you will save about 20-50% of monthly spendings. You need to know how much each dish costs and how long it is enought, knowing the cost of lunch and dinner. For example, rice and milk soup is enough for both lunch and dinner, and the cost of the dish is 5 times lower than other dishes (5 times more affords), like tasty spaghetti and others. Knowing the prices of lunch and dinner - improve food preparation. Eat healthy by adding vegetables to your dishes time after time you eat. Eat healthy and cheaply, but ALWAYS once a week, on weekends, be sure to make meat dishes rich of all various materials (or cutlets with a mix), like a weekend celebration. Choose cheaper dishes every day (morning sandwiches, hot sandwiches, spaghetti, rice soup, baked potatoes, pancakes, porridge with applesauce, sandwiches with mayonnaise and cheese for all week, "Nutella" for night snacks, which is enought for a long time), but on weekends don't save, make everything as more delicious and diverse as possible.
Calculate everything not by the prices of products, but by the prices of dishes. You will save monthly money for things and leisure, you won't eat money. You will save $100-$400/month by counting dishes prices.