Control is a pretty big part of it, but I tend to throw mine with the flat of the foot while sparring. It is still pretty rough on your sparring partners, but exponentially better than the heal making contact. I spent several years working it against a bag and the air prior to using it while sparring. It sucked to work it so much and not use it right away, but it payed off in the long run.
Originally Posted by gregaquaman
As far as set-up for the lead leg goes, I use jabs and "gimpy" backfists to get my hips into position, after working my opponent towards a corner. It makes it higher percentage, but it is still not super high. I have also used it directly after a clinch, but this faded once my spinning hook and axe kick came along. More often than not, the lead hood should be used as a defensive kick, IMO. If you have the speed and flexibility to work it that way. It works well in a knockdown karate situation. Kickboxing, less so, as opponents tend to have lazy hands in KD tourneys.