Here is something I learned 35 years ago working as a mechanic. I ALWAYS install spark plugs using a soft pliable length of hose that will fit over the tip of the spark plug firmly and is about 10" long. There use to be some green hose used on the smog systems 35 years ago that is perfect the job and still works today.
By using the hose, you can get into tight places and the flexibility of the hose allows for starting the spark plug at the correct angle. If it starts to cross thread, the hose will spin on the plug before any damage is done.