Do not leave unattended. Ever.
Drown, stir, feel. Repeat as necessary.
Keep the fire small.
Only on mineral soil - remove all organic debris before building.
If not in an established ring, remove all traces before leaving (after extinguishing completely).
I'm one who enjoys a campfire, but I generally only make one if I need it for cooking, or am in an established campground (car camping) where I generally buy the wood from the campground host. I like using the Bushbuddy and other mini wood cookstoves, but they use only a tiny amount of twigs, burn to ash and cool quickly. A campfire per se tends to be big and use a lot of wood (especially if there are many young men involved!)which tends to denude the local environment.
Added: I've seen some videos of fire building and campfires from the East Coast which, if down out here in dry Western mountains, would result in massive forest fires - things like building campfires within a hands distance of dead leaves and other organic debris. Horrifying out here!