Nothing extra needed at all. A proper fitting mask will seal nicely with a reg in your mouth. Yes, some water may enter, but you get the same thing with experience lines around your eyes. Don't trim anything, stubble leaks more than errant hairs. I clear my mask occasionally throughout the dive but that is generally because I move it doing a vassal clearing.
I don't shave or trim anything on my face to better seal my mask. My stache gets trimmed off my upper lip to prevent me chewing on it, but not away from my nose. Cheeks and burnsides are untouched.
Edit: fwiw I dive a Mares X-Vision