I pick them all up by the tail, I don't trust getting near their mouth and chance getting bit. Don't use tongs or hemostats on live rats or mice, it hurts them. For live rat pinkies just drop them in by the snake. Some say that picking them up by the tail can hurt them but from my experience it only is a strain on the very large jumbo rats that are over a pound in weight, that's a lot of rat to hang by the tail. I'd say it's fine for the small and medium rats.

Also, never dangle a live rodent by the tail next to your snake, it stresses out the rodent and the rodent will actually bite the snake if it gets too close, believe me, I've done it a couple times. Never again. Just drop the rodent in the tub / tank with the snake and let him relax a bit!