Is you are unsure if you are at a healthy weight, ask your doctor or a registered dietician. They will refer to height and weight charts or calculate your body weight index to determine if you are overweight. There is no best way. Rigid diet plans do not fare well in most cases. Since each person has a different lifestyle, food preferences and activity levels effect energy requirements.
Most people do better with a personally tailored plan.
Ask your doctor to refer you to a registered dietitian in your area to help you start. Start off with keeping a food diary of everything you eat and drink for at least a week. Include everything, paying close attention to portion sizes, i.e., measurements such as cups, ounces, etc. Include snacks such as a piece of candy, a pretzel, or food you munch on during meal preparation. Review your food diary to determine if there are times or situations when you could make better food choices.