I try to plan out my meals at the beginning of the week. I also try to plan my meals around what I already have in my pantry and refrigerator/freezer. I try to buy what is on sale and keep my pantry/fridge stocked with staples that I can cook meals from. On weeks I am trying to save money, or I don't have a lot of money, I try to (or am forced to) cook solely from the stock in my pantry/fridge. I also try to make a few meals out of one meal. I love leftovers, but my husband gets tired of eating them, and so does my daughter. So, I plan meals so I can makeover my leftovers.
For example, dinner at my house last week (carried over into yesterday, and lunch for today and tomorrow):
Meal #1: A whole chicken in the crock pot served with vegetables I have on hand.
Meal #2: Leftover Chicken made into a Chicken Broccoli casserole
Meal #3: Leftover Chicken made into Barbecue Chicken Pizza (I was going to make chicken salad, but John requested the pizza)
Meal #4: A big ol' pot of home made Chili
Meal #5: Leftover Chili made into Chili Cheese Cornbread Bake
And, usually we have leftovers from the leftover makeover meals. Now, I know because we have a small family we can make our meals stretch a little farther, but if you have a larger family, you can still do the same thing if you plan ahead to make larger quantities for the first meal. Those are all meals I can make with the staples I have on hand, and all inexpensive meals. Figure out what your staples are and you can do the same thing based on those. Another cheap meal is spaghetti; make a large amount, and you can turn leftovers into baked spaghetti (bake your leftover spaghetti with cheese on top), or spaghetti pie (basically lasagna with spaghetti noodles). This really helps stretch my grocery budget when I need it, and makes it really easy when I am too tired to cook, and I can just throw stuff together!
Broccoli Chicken Casserole: Reserve and strain broth from your whole chicken. In a casserole dish, add about 2 c. of shredded chicken, 1 c. of reserved broth, 1 small bag of steam fresh broccoli, 1 can cream of chicken soup, 1/2 - 1 c. sour cream, about 1 c. of cheddar cheese, 2 c. of rice or noodles, and a little bit of milk to make desired consistency. Cook at 350 degrees until bubbly and heated through (about 30 minutes). You could also add stuffing (Stove Top or homemade breadcrumbs, whatever you have on hand) on top if desired.
Chili Cheese Cornbread Bake: Put leftover chili in the bottom of a casserole dish (I use my cast iron skillet), sprinkle 1-2 c. shredded cheddar cheese over top. Make your favorite corn bread recipe, or if you are really tired, I guess you could use a cornbread mix, like Jiffy, or something. Pour your cornbread batter over top of your chili and cheese. Bake casserole at the same temperature and for the same length of time as your cornbread recipe. (Warning: If your cornbread recipe is baked at 350 degrees, I would use a higher temperature, especially if you are using a cast iron skillet, or it is going to take a long time to get the middle cooked.)
One of my biggest budget and time saver tips: Almost five years ago, I discovered the beauty of cooking with whole chickens. I stock up when they go on sale for 47, 59, or 69 cents a pound. When I cook them, I stick the whole chicken in the crock pot and can definitely make more than one meal with a one chicken. You really can't beat the price and the time it saves you. It's so easy, and crock pot cooked chicken is always so moist and yummy; no hard, dried up, or fatty pieces of gristle attached to your chicken in your foods!