One of my favorite parts of being a parent is the balancing . . . and the nudges of information. . . "You know, if you want to climb on that [fill in the blank of something not really supposed to be climbed upon] you can, but if you fall, it just might hurt."
Balanced with, "Get down from the top of the wooden swing set now." [There is no negotiation because one fall now probably means a trip to the ER for some stitches.]
Drawing the consequence lines - some you can experience (and learn first hand today), others we ought to wait for another day.