I've written about Glyn Dewis before on Fstoppers. He's a fellow Photoshop World Instructor, UK-based photographer, and has an amazing blog and youtube channel filled with great image post-production tips. In this tutorial, Glyn teaches how to add nice detail and grit to your portraits, as he did with his boxer portrait series featured here. Click to see the entire post to watch another tutorial video on this shoot.
Below is an overall behind the scenes video from his champion boxer shoot as well:
Feel free to ask questions below for Glyn. He's normally a very friendly and responsive guy and a great instructor. Make sure to check out his blog and youtube channel to learn more. He even has more posts from this and similar shoots about his lighting technique as well.