It would depend on what are youre goals. If you would want to add mass it would be necessary to do bouncing/ballistic (carefully) stretching so to conserve power (passive stretching reduces power during workout. jogging or riding a bike will amp up your heart rate. Sometimes calisthenics, or low weight exercise will suffice for a warm up. The type of exercise, weight and duration will depend on your goals, your body make up or what are your training will be. Usually 30 minutes is needed if you are young and need to burn calories.