The #1 thing that I have client's look at on a nutrition label is the grams of protein. A food that comes with 30-40% or more calories from protein will be satiating and fat burning. The easiest way to determine if a food is a high protein source is to add a zero to the grams of protein. Compare that number to the calories per serving. If it is equal to or greater than the calories per serving you know that 40% or more or the calories are coming from protein. This will be a food that makes you feel full and helps your body burn fat NOT store it.
When reading food labels at the grocery store, it depends on what you are focusing on for your health. If your goal is for heart health, you would focus more on sodium, fat, and fiber. If it is for diabetes, you concentrate on these items, plus total carbohydrate grams. If your focus is weight loss, you would look more at calories, sodium, fat, fiber, and protein. With food allergies or Gluten Intolerance, you should focus more on the ingredient list. A good rule of thumb is that under 5 grams total fat, 0 trans fat, >3 g fiber, <300 mg sodium, and < 10% added sugar is a good product. Also, the first three ingredients on a food label is the most prevalent.
One of my best tips for reading food labels and making informed choices at the grocery store is using ChatGPT. I've started scanning ingredient list/label into ChatGPT and asking it to quickly summarize what's good, what's questionable, and if there are any hidden additives or sugars. It saves a ton of time and helps you catch things you might otherwise overlook. When reading labels, people should pay close attention to the first few ingredients listed, they make up the bulk of the product. So if those ingredients aren't good or you have no idea what they are, best to skip that product!
I look first to the total number of calories and try to find foods that are in general not heavy in calories. I then look at fat content and choose foods with lower fat. I also look at added sugars. I prefer foods that have no or little added sugars. My main recommendation is to avoid added sugar to avoid sugar spikes and the inflammation that can result.