What is the most effective weight loss strategy/technique for a 20 year old male?

Eat fewer calories: Most people are successful at losing weight when they eat less every day. It's usually a matter of finding out what what are healthy portions of healthy foods. This doesn't mean you have to stop eating the foods you like. It may mean learning to eat other foods and reducing the overall amount that you eat. Being physically active most days of the week will help keep pounds off.