Some tips/advice:
1) Stop drinking soda, iced tea, or drinks that are heavily sweetened. Opt for water of seltzer. If you drink, say, 4 cans of soda per day, that's already 520 extra calories you're shedding. Instead, have water or seltzer water (flavored is okay.) If you're in the U.S., chances are a lot of your foods are sweetened with HFCS (high fructose corn syrup). There are some studies linking this to larger amounts of fat around the waist.
2) Opt for whole grains instead of white breads. Most white foods are starches and turn to sugar the second they hit your blood stream. Whole grains are better for your heart and arteries.
3) Drink a glass of water before a meal. This will take up some space in your stomach so that you'll eat less.
4) Eat slower and savor your meals. The quicker you eat, the more you eat.
5) If you're fond of salad, watch your salad dressings. If you're fond of chips, try to switch to baked or kettle-cooked ones.
None of this is really ground-breaking advice. If you're trying to switch from, say, soda to water, do it gradually. It's difficult to go cold-turkey.
Also, be smart about this. Don't cut your caloric intake from 3,500 calories to 1,500. Your body will try to hold onto weight. Keep in mind 1,200 calories is considered the absolute minimum the body needs to function. Most adults need closer to 2,000 calories, but usually slightly more. I will say, though, I feel healthier since I've stopped consuming soda and caffeine. Some of my sleeping problems have been alleviated and/or eradicated. Small setbacks are normal and to be expected. Just saddle back up. Finally, I find it's okay to indulge every once in a while, as it helps cut back on cravings.
Finally, a disclaimer. I'm not a doctor. All of this information is available on the internet. Be careful, be smart. Talk to your doctor if you have concerns about your health and starting a diet.