Begin increasing your flexibility by practicing stretching daily. Sit on the floor with your legs spread apart as far as they will go and lean forward slightly to stretch your muscles to the limit. Hold the muscle at its maximum for 30 seconds at a time, both in the center and on each side.
Extend the time you hold the stretches to 60 seconds after you no longer feel as though you are straining to hold 30. Each time you stretch, pull the muscle to its limit. This will ensure that you continue progressing as your muscles condition.
Begin holding the split position for 60 seconds at a time once you are flexible enough to reach it, which could take weeks to months of stretch training, depending on the individual. Once you are able to, lean to one side and hug your leg with your face pressed against it.
Stand up against the corner of a wall once you are confident in your body's ability to safely hold the position you have been practicing. Lift your leg and place your heal against the wall for support as you lean into the stretch, until the head can comfortably rest on the leg.