Make your shopping list ahead of time. Avoid spontaneousely picking items at the store. Chances are, you will be picking up something that you don't need, and/or is not good for you. The only exception is if you see an item that you needed, but somehow forgot to add to your list.
Don't spend too much time looking around at the store. The more you look round, the more your attention will be focused on things like ice cream, potato chips,cookies, chocolates, and other such items.
When shopping for ground beef, absolutely stay away from anything with more than 15% fat. The lean meat costs a little more, but the hospital bills later are a much bigger problem with eating fatty food.
Try to limit use of red meat as much as possible. If possible stay away from pork and lamb as well. These meats have a great deal of fats nd cholesterol, and are a ateway to high blood pressure.
When you get a choice, pick the lowest fat content on cheese, milk, sour cream, and other dairy. The fat free items taste much much better than they used to.
Get frozen yoghurt, or fat free ice cream instead of the regular kind. The taste is not significantly different.
Baked instead of fried when shopping for chips.
Get fat free baked beans instead of refried beans with lard.
Absolutely stay away from regular hot dogs. They are literally made of all of God's creatures. Just look at the fat content of one hot dog. Get the Turkey Breast type deli meat with fresh baked bread.
As for oils, the oils that are in liquid form in room temperature are generally better for you. Canola and Olive oil are the best. Butter, and lard are the worst. I would also stay away from Palm oil. You want oils that are unsaturated.
Chicken breast that is skinless and boneless is the way to go. If you are willing to do the deboning and deskinning the meat, then get the breast with ribs.
Ground Turkey instead of ground beef is another option.
Buy vegetables, and plan to use them. They are dirt cheap, and very good source of anything that meat does not give you.
Get fruits. Focus on fruits that you do like. Watermelons, Apples, Oranges, and Grapes are around year round. Bananas and strawberries are among other favorites. Stay away from avocados. They are fruits, but they also have a lot of fat. Not a good thing.