What should we look at on food labels?

Five ingredients: I highly recommend a book written by micheal pollan called food rules. Only buy food that has five ingredients or less. If you follow this rule you will be forced to buy unprocessed food which is generally the healthiest kind. Don't buy food that comes in a box, is microwaveable, or prepared by someone else. Buy wholesome ingredients and make your food yourself.

Be aware of pitfalls: Food labels have been a great boon for the nutrition-conscious, but the information can mislead. Examples: calories are rounded off, so zero calories just means less than 0.5 calories per serving. If a serving is one shot of a flavoring spray, multiple zeros do not add up to zero! the number of servings can also be misleading. If you eat the whole container, multiply by the serving number.