I lost 30 lbs last year by adjusting my diet. I basically followed a low carb and increased protein diet. I also drank lots of water. My wife also lost 17 lbs following this basic diet plan.
I followed the Dukan Diet. But the biggest thing I learned is just eating less. Instead of getting a 2nd helping, skip it. Don't late at night. Eat healthy snacks like low fat yogurt instead of chips and candy bars.
There is no magic bullet...just careful planning and commitment to do it. If you fall off the wagon, don't sweat it. Just get back on the plan.