After wasting filament once, I do a quick scale check on scrap. It only takes a minute but catches mistakes early. That habit has saved me from several bad prints.
Actually, I always do the scale check before I even slice. The slicer can mess with things sometimes, but if your model is way off from the start, you're already in trouble. I open the file in the viewer and just eyeball it against the build plate. It's saved me from slicing a tiny keychain that was supposed to be a vase.