[crazy voyager]

I let players be in for a few secs (5-6), then I start counting with my hand, showing that I*m counting, usually they get moving then, if not, I call the violation.
With younger players (on low baskets and such) I tend to call "watch the 3-seconds" or "get moving" and they'll mvoe. There's no need to call 3-secs on the small ones unless they stay in there forever, but the older they get, the harder I call it. With our oldest girls I don't warn either, I sikmply call it, but they're so good that thye stay out automaticly anyway :P so it's not many calls anyway.