Hello Nick,
I prefer the side ways split or chinese split to help one with the roundhouse kick,along with any exercises that help to loosen up the hip muscles.One exercise that I like, is to get into the front split and slowly turn into a sideways split.Another one is where you stand and put your leg on a support as if to do a front hurdlers stretch and after doing the front stretch turn your body into a side kick position and rotate your body as far back as you can to thouroughly work that hip area.After a while you can start raising the support to a higher and higher level,thereby increasing the difficulty and extending your range of motion.One good thing to remember is that your back muscles have alot to do with it so you want to make sure that you warm up properly.Always make sure you stretch before and after a good workout,and warm or cool down slowly as this will help to avoid lactic acid buildup in your muscles and help you to keep from getting those nasty cramps.Which are associated with cooling down to fast.
Take care,
Your Brother in the Arts [IMG]http://www.fightingarts.com/forums/ubb/smile.gif[/IMG]