Years ago, I developed "Five Rules for Healthy Eating" that I've been asked to share. Several people have told me they lost several pounds and saved money after adopting these rules!
1. Eat on 8" plates.
If you fill an 8-inch plate and then transfer the food to a 9- or 10-inch plate, it goes from looking like plenty to looking like little, tiny islands of food floating around a vast ocean of empty plate.
2. Don't eat anything containing hydrogenated fat.

These fats are also called trans fats, and our society has done a pretty good job of reducing these in our available food sources.
3. Don't eat anything containing high fructose corn syrup.
This one is tough for me. My corn-producing dad chewed me out for preaching against consumption of a product that increased value of a commodity he raised. Okay. So have a Coke now and then. But not every day.
4. Drink water, coffee, or tea with no additives.
Sports drinks, diet drinks, flavored teas, lattes, and other concoctions add a lot of calories. Try to avoid them. They are also expensive.
5. If you didn't grow it, wash it, prepare it, don't eat it. (Don't eat out.)
Eat real foods, avoid processed foods, and don't eat at restaurants. Cook. There are millions of recipes on the internet. Invest in a Crock Pot. Plan ahead. Shop wisely. Avoid any foods that come prepackaged and "easy" to prepare. They are probably full of stuff you don't need to eat! Eat out only for special occasions, not for daily convenience. This rule is the one that prompted a college student who worked for us one year to save several thousand dollars. And lose 15 pounds.
If you are over 50, here are a couple other thoughts to consider.
Ease away from a heavy evening meal. Years ago, my Honey decided to lose 25 pounds during Lent, that six-week period in late winter/early spring that follows Christmas eating and winter stocking-up. The biggest change he made was switching to a salad for supper. He said it was tough for the first three or four days, but then he got used to it. He ended up losing 28 pounds. And kept it off.
And, though it pains me to say it because I love to bake, you may need to limit consumption of wheat flour. This doesn't apply to everyone. My in-laws are both very trim octagenarians who eat bread. However, for many over age fifty, breads, cakes, cookies, and pies mean water retention, pants that don't button, and bloating.