I know I'm not the first cisgender female to write male/male romance, or to write about being a female writing male/male romance :D. But here it's on my mind. Most recently it's because of the time spent with three male characters- The Queen, Tommy, and Raanan. I'll give you the links at the bottom, if you'd like to read some male/male/male (the number switches by scene) sex and BDSM.
In many ways, I try to relate on things as I can from my own experience. I absolutely adore anal sex so I feel pretty confident in writing anal sex between two guys from the receiving end. Also a whip feels like a whip dependent on the fat deposits on a part of a body- my very masculine Master's calves aren't (respectively) really thicker than mine. And submission has its roots, not so much in one's gender unless that is a specific source for a person. Then there's the fact that I prefer to watch gay male (especially leathersex and bears) porn. So "what it looks like" is completely doable. I have watched and read far more male/male porn/erotica/erotic romance than male/female.
The big thing for me, is that I try to envision my characters as far more than their gender.
Long, super straight black hair. Large, strong body. Strong, capable hands. Beautiful bright blue eyes that show such a well of compassion, caring, passion. A countenance that gives such joy and dozens of other wonderful emotions to loved ones. The most fantastically kissable lips. Strong legs that can only lead the person viewing them to think about sex. Desire to help all those who need it. A wonderfully big, affectionate heart. Attention to details, especially those that make lives better. Dominant over a lovely stable of BDSM slaves. Sometimes dom/top to a loving best friend. A bit of a switch to the loving transwoman who taught a higher level of caring.
That description of The Queen- was there any mention of his genitals (which btw I love to write about :D) or his gender (as he does identify as a cisgender male, even if that terms wasn't in use yet in the 1990s, when Vala's Story is roughly set). While it was a little tricky at points, I even managed to write that without using any pronouns. Yes, he is a male with "dangly bits"- oh how I roll my eyes when I see that phrase. But his sexuality is so much more than what he does with them. There's the simple order to a slave: "Kneel up." Of course, in my imagination, it's his deep, gravely, growling voice that makes me shiver, but then I like bears. And I found me a manly man to beg His collar.
So I try not to be "that woman writing male/male action because it's hot but having no idea how it would really look, feel, smell, affect the participants etc." I think about not wanting to misappropriate another's sexuality, but I'm writing a queer, BDSM, polyamorous erotic romance that seeks to move beyond boundaries, often even the ones that I willingly use to describe it. I guess I'll have to just risk offending someone :D.
And the links...
First here's The Queen making love to Abrecan, although on the page, there's links to the first 3 parts of the series (with Tommy and Abrecan, then Tommy preparing Abrecan). http://joellecasteel.blogspot.com/2013/09/the-queen-makes-love-to-abrecan.html
And while it isn't male/male, but female/male, here's a link to Raanan and Vala, which kicked off an interesting two part series (still to post) where Vala manages to top Raanan. These were written in Raanan's POV, forcing me to stretch my imagination. http://joellecasteel.blogspot.com/2013/09/satspanksvala-isnt-trying-to-be-brat.html