Writing advice is a mixed bag. Sometimes you'll hear something so pertinent that it will rock your world. While I'm definitely not a pro at this point in my career, I've found that I give novice writers the same advice year after year:
You can't edit a blank page. I mean exactly that. No writer can move to the next step in the process, the editing hell, without words on a page. It seems simple, but some people, including me get so trapped in their heads that the story doesn't make it to the page.
Sex scenes are like fight scenes. Hear me out. You, as the author, need to be aware of and make clear to the reader where everyone's limbs are at all times. Otherwise, it just gets weird REALLY fast.
The best advice I've ever received comes from a fellow writer whose workshop I attended at a writer's convention.
"Write slow to read fast."
I initially didn't get it, but I figured it out. Some sex and/or fight scenes are so short that it's impossible to know who did what and how. It can be a stylistic choice, and that's cool. My writer friend meant (I think) that you have to fill out the details even if it makes the scenes longer. If you have the right kind of details and plenty of movement, people will flip through the pages with excitement and want to read what's next.
One should also keep in mind that real fights don't last an hour. They're barely minutes long, especially if there are weapons involved. Write it slowly. Write the actions, emotions, scenery, and annoying clothes that get caught on a sharp edge and throw the protagonist off. Did someone yank on your MC's hair and throw them to the ground? Where did that knife come from?
You get it.