It's something you do every day, as routinely as cleaning your teeth, but chances are you're doing it wrong.
Yes, we've got tasks such as shaving and toenail clipping down to a fine art; but something as simple as keeping the crowning glory clean is not as straightforward as you might think.
The fact is, most men don't know how to wash their own hair. That's especially heinous as many are rubbing in ever-increasing amounts of gel, wax, paste and mousse in an effort to look sharp.
"A lot of guys use shower gel on their hair, or the cheapest shampoo they can find in the supermarket," says Jo Smith, of Toni & Guy Georges in Melbourne.
"Eight out of 10 men are using shampoos that are too harsh. There's this mindset 'I'm just a guy; that'll do'."
But all that these cheap shampoos do is strip the hair and scalp. They're harsh. You might as well be using dishwashing liquid.
What you can be left with is a type of oily dandruff. "The scalp thinks it's dehydrated so it produces more oil to compensate, leading to excess sebum," Smith says.
And now, as they say, for the science bit. Sebum is the oily, waxy stuff that's secreted from the skin's sebaceous glands to keep hair shiny and flexible. You need some, obviously, but making your scalp think you need more? You end up with oily dandruff. Yeuch.
I got my scalp thoroughly and properly cleansed the other day and it felt so good. Mark Rippon, who revels in the title of Shu Uemura's Artistic Master, offered to spend an hour cleaning and rinsing and massaging my scalp.
I was a bit nervous at first - especially after he brushed my hair for about 10 minutes and made it stand up as if I'd stuck my finger in the light socket. But it was fabulous. I always think the pre-scissors shampoo is the best bit of a haircut, and this was like that for a whole hour.
It's like the next level in pampering and left my scalp feeling cleaner than I can recall without the constant low-level itch I get, especially in winter.
That itchy feeling is probably because men also use far too much shampoo, as if we need a huge head of foam to get clean.
"Men get through shampoo too quickly, which is one of the reasons they shy away from good shampoos," Smith says. "But a professional brand lasts six months."
A dollop of shampoo the size of a 10-cent piece should do it, and Smith suggests men use shampoos containing menthol, peppermint or tea-tree (American Crew and Label M both do good ones) so the hair and scalp feel refreshed and rejuvenated.
They also have an anti-bacterial effect. A nourishing shampoo means you don't need to use a conditioner, unless your hair is long and curly, Smith advises. "Men with shorter hair, they never get 'old' hair. A nourishing shampoo is all that's needed." Along with a thorough rinse.
Do you think you know how to wash your hair properly? What's your method?