but how to do it is as important or more. A great tip I got right here in YT was to use a small comb to keep the scissors from touching the skin

. I had used the electric trimmer and they were liking their butts for days (I think they got razor burn or maybe I cut too close). Also, make sure the scissors are pointing down or to the side in case they move their tail. I always enlist the help of their daddy when I use scissors, to be on the safe side.
I always clean them after potty even if the poop is solid because after doing it for so long, they expect it (they come inside, lift their tail, stand still and wait to be cleaned) and sometimes they look clean but they're really not.
I always use a slightly damped paper towel or unscented, hypoallergenic wipe, never dry. My HB uses dry and they run away from him (HB is also a little rough--he rubs, I dub gently).
Go on Youtube and search for dog grooming to see how to's