What Renn said.
If you allow them to do something the novelty wears off, and they'll move on.
Anything you don't want them to touch- move it or block it off so they can't.
If they get hurt shutting doors or cupboards, touching a hot cup etc they won't keep doing it! Mess can be cleaned up.
My dd trashed the joint getting into everything for a little while around that age but then stopped as there was nothing new to touch or go through and no attention in doing it either.
Eta: I actually miss those days. At least she kept herself entertained without involving me. I never bothered with saying no or stop over and over as it was a waste of time at that age-
Save stop for when you really need it.