Not a parent, but I have a cousin who's doing pretty well with her 4 kids, discipline wise, at least I think so. The kids are nine, seven, four and two if I remember correctly. I usually dislike her methods of doing shit because she abuses the fact that my aunt just can't say no to her own daughter, but when it comes to disciplining the kids, both of them (aunt & cousin) do the same thing. If the sprogs were near something they shouldn't be near, they'd tell them to get away three times and on the fourth time if they were still there they'd get a small slap on the hand/wrist. They get an automatic and slightly harder slap if they hurt a sibling or say something they shouldn't like real bad profanity aimed at the parents or siblings, used in school etc. Yeah, all right, they cry and moan but they learn their lesson. Taught me many a lesson.
Specially when I was an itty bitty pyro at six years old who loved throwing things into the fire.