My favorite subject.
Never use the word "Diet" you set your self up for failure. Losing weight and maintaining your ideal weight is about "Life change". It's actually easy to lose weight, it's harder to maintain it once you lose it.
Losing weight is all about two things. Food and Excercise. Don't deprive yourself of food to lose weight. You have to eat to lose weight. Eating 5 or 6 small meals a day is the perfect way to keep your motor burning and burning calories all day long. Never miss Breakfast. It's like starting your motor. You want to feed your body with fuel (food) every 3 to 4 hours to keep your metabolic rate working.
Foods to avoid are almost anything white. Bread, rice, potatos, etc. I eat whole wheat bread, Brown rice, Sweet potatos, etc., There are a ton of good foods to eat. Just avoid chips, fast foods, and the high carbs stuff.
Pretty easy really. I snack on almonds, protien bars, yogurt, etc., I also eat two MRP's day. (Meal Replacement Powders). These are great for one or two of your 6 meals a day.
Excercise is the key though. I lift two to three days a week and run 4 to 5 times days a week. The best excercise for burning body fat is interval training on a treadmill. It only takes 20 minutes and is "High-Impact" training. It basically consists of Walking, jogging, and sprinting in 30 sec to 1 minute intervals for 20 minutes. It's tough but if you want quick results, try it.
Don't think you have to drink water to lose weight. You need to keep your body hydrated but water isn't the only solution. That theory is overrated. You can drink diet pop, unsweeted tea, etc. Just make sure it has no calories in it. People tend to drink to much of their daily caloric intake instead of eating it.
I weigh 185 and I'm 6'1. Ive maintained my weight for 10 years now. I started out with the body for life program and then adjusted it to fit my needs.
There's a lot more you can do. But those are some things I would suggest.