Pre work out strecthing is very important. It reduces the chances of season ending muscle pulls.
Always stretch before work outs or practices.
For the legs start with the calves first. Place your hands flat against a wall, making sure your feet are flat on the floor, let your body come forward and you will feel the calves strecthing. Another benefit is you should feel that hamstrings getting a pre stretch warm up.
When stretching the hamstrings sit on the floor and bring the right hand to the left foot and vice versa. This will stretch both the hamstrings and back muscles.