Today's tip is to buy less processed/boxed food. Start with just two or three less items, and work towards as few as possible.
The trade-off with buying less processed food is that you have to spend more time cooking it yourself.
Some of the easier things to start with -
1. Cake, etc. mixes. It is easy to create a cake from scratch. It doesn't take much more time than adding the ingredients to the mix.
2. Spaghetti sauce. I haven't bought spaghetti sauce from a jar in probably two years. It is really easy to make it yourself - two bigger cans of tomato sauce, 1 can diced tomatoes, 1/3 cup brown sugar, 2 T. olive oil, spices (garlic, oregano, basil, etc.), and dried onions. Bring to a boil and then simmer for 15 minutes. If you want ground meat in your sauce, brown it and then add it to the sauce after it boils. This makes up enough for about 10 servings, so I usually freeze the leftover sauce.
3. Chicken Nuggets. Cut chicken into nugget sized pieces. Put bread crumbs and any spices you want in a bag. Shake and then bake them for about 15 minutes (depending on how many you want to cook.) You could probably put flour and spices on the chicken chunks and fry them instead, but I never do that.