If you shave your head, where do you do it? Bathtub? Shower? Bathroom sink? Kitchen sink? Back yard? Neighbor’s guest bathroom?
I shave mine in the shower, with the water running. If I get it 2 or 3 times a week, I both both razor burn and clogged drains.
So how do you do it?
I’ve recently switched from the bathroom sink to the shower.
Ironically, I’ve been doing a better job because me sense of touch as I use my hands to decide where I need to shave is much more scrutinizing than my sense of sight.
Plus, any excuse to stay longer in that intoxicating warm shower is alright by me.
It has been many years since I shaved my head with any regularity, but I always opted for the sink, because sinks are generally much less of a hassle to unclog without enlisting the aid of a tradesman. (Never actually had a problem with clogging, but it seemed a sensible precaution.)
I do it standing over the garbage can. Most of the hair falls right in, no need for major cleanup.
I shave my head using an electric clipper with a #1 guard every two weeks, and I do it standing over the bathroom tile floor. When I’m done, I just use a dustbuster to vacuum up the short hair, and step immediately into the nearby shower to hose myself down.
In the shower with a Gillette and just bar soap for lather. Usually three or four times a week.
Shower, with no water running. I clear out all the hair I can and then shower. No clogging problems yet.
In the shower, water running, with a Fusion, every morning. I have a “no-fog” mirror on the wall, and just shave after washing. I clean out the drain grate every week, but there seems to be more cat hair caught in it than my hair.
Neighborhood carwash! 
Actually, I shave almost every day in the bathroom sink. Everyday shaving is just like other whiskers: short, easily cleaned up.