So much of portraiture is of women that you would be surprised at just how much posing knowledge you might have without trying. However, for many reasons, with men, it's trickier. This video goes into some tips, tricks, and mistakes when posing men for portraits.
I distinctly remember my first shoot with a male. I had an idea for a shoot — which in retrospect was something of a trope of portraiture — where I would have a male wearing a suit smoking; think something akin to pictures of The Rat Pack. For all of my creative flaws as an inexperienced photographer, I had another lesson due to me: I had no idea how to pose males.
It wasn't a problem per se as I had a good relationship with my subject and so there was very little pressure to get it right. I was also an amateur and the shoot was for fun. However, it wasn't until he was stood in front of my camera, I had got the lighting how I wanted it, and we had sorted the wardrobe and details, that I realized I wasn't sure how he should stand. I'd looked at so much portraiture of women over the years on websites like Flickr and 500px as well as in magazines, that I had immediate ideas. With men, however, my coffer of poses was dry.
This video by photographer, Jerry Ghionis, is a brilliant brief education on the topic. While some of his tips are useful, what I think many will benefit from is his understanding of what doesn't work and mistakes you can avoid.