You can use a site like fatsecret.com to count your calories
Drink water. Replace all of your daily intake of fluids with water. No soda, No juice, No milk. Just water. This way you aren't drinking your calories. Though I do occasionally indulge in a bit of OJ or milk sometimes when I get the craving. No use in denying myself something that is only going to make me binge later if I don't have it. Also, you should drink a protein shake after your workout everyday to keep your muscles strong. It wont necessarily bulk you up or anything too bad so dont worry about that. You can even use it to replace a meal if you want.
Stay between 1200-1400 calories per day.
When you are done eating at each meal you should brush your teeth right away so you aren't tempted to snack unhealthily between meals.
Stop eating at least 3 hours before you go to bed.
Try to cut out added sugars and stick to ones that are already there. If you need something sweet try strawberries or grapes or other fruits like melons.
Eating a banana before you workout will help give you a rush of sugar/energy and keep you on the right track for success.
Try replacing hamburger meat with ground turkey. Bacon for turkey bacon. Regular eggs for just egg whites. Etc.. Small changes make a huge difference.
Eating fresh spinach in salads is better than iceburg lettuce which doesn't have much nutritional value. The spinach is good for your iron intake and isn't just filler in your tummy.
If you want something to snack on that's easy to grab then instead of getting a bag of chips you should try this. Divide your foods up by serving size, beforehand, in to small ziplock bags so you aren't tempted to overeat. For example, I just divided a bag of babycarrots in to what the serving size said. It says there are approx 10 servings per bag so i got out 10 ziplock bags and made sure there was the same number of carrots in every bag. Then i did the same with my wheat thins. It said 14 servings with 16 crackers in each bag.