1) Deep Frying
Deep frying can increase the calories of a food by over 40%. Not to mention it significantly increases the amount of fat. Some fat is necessary in the diet but deep fried foods are often high in the wrong kinds of fats. For a healthier choice: focus more on grilled, BBQ'd and baked options.
2) Processed Meats
Research is starting to link the effects of processed meats with heart disease. For example, eating one ounce of processed meat per week can increase the risk for heart disease by a third. THIS IS HUGE! Try to choose fresh or frozen unprocessed options like chicken, fish, pork chops and steak. Red meat can be included in moderation as part of a balanced diet but the unprocessed versions will be a much better choice.
3) Box Foods
Think of it this way: the less hands that handled your food, the more control you have over what is in it. Many prepackaged foods are high in cheap oils, sugar, salt and preservatives. If you have the option to make something from scratch, do it.
4) Sweetened Drinks
Calories from sugary beverages can add up. Even the healthier looking options like a simple cup of all natural fruit juice can have over 5 sugar packets in it. These harmless drinks in a day (a smoothie here, chocolate milk there, sugary coffee in the morning, a can of pop at night...) can sometimes lead to you drinking as many calories as you eat! Focus more on sugar free options such as water or plain coffee and tea. While sugary drinks as a treat are totally acceptable, the less you make them a part of your everyday life the better. These drinks do nothing to fill you up but can really raise your total calories in a day.
There are lots of other things that can help you improve your health, be sure to check the rest of the site for more tips!