If you have a young horse, you can probably "kick first" with good effect. With an older horse, or a timid horse, I'm not nearly aggressive or brave enough to challenge a kicker, and make a point of staying safe. (Far enough away-- and be aware some horses can kick sideways too!-- or with a fence between.) Strangely enough, over time, the kicking syndrome has diminished when there's no reason for it. If a horse kicks, and absolutely nothing happens, why bother? With the 2 bad kickers I've had, anyway.
Another thing that helped with one was, I was washing her off, and she started kicking, and I just ran the stream of water on her legs as she kicked and kicked. I stayed very passive, though it was alarming, but after that episode she hardly ever kicked again, for any reason. Sometimes she'd kick as a reflex, if startled. One should always be careful around horses.