My measly two cents. Find some writers who do it well. I read Joe Abercrombie and really liked how he wrote action and fight scenes.
For me, they are a challenge, but here is my process:
I draw it out. Using X's and O's that I "name" and whatnot. I draw arrows and see how the physical space will look and where people will go. What character will SEE or NOTICE what from his/her perspective. Will Charlie over here notice what's going on way over there where John is? (That sort of thing.)
Once I get that game plan down, I write up a very terse/sparse outline or sequence of events. Charlie moves in from the left and draws his weapon. Bad guys react in THIS manner. Just kind of a list. Then I work from that, seeing what I need to include and actually spell out in detail and what is assumed. Having it all outlined for ME helps.
After I get the action in and have a solid section, I ask myself if I will have any internalization or any moments of thought or thinking where I am close into a character's POV. I will add those in last. Those tend to really add dimension to a scene, to build tension, and to create urgency. I read the scene in Game of Thrones to my students (when I am teaching them about fight scenes), where Arya is working with her swordmaster, Syrio, and the Lannister guards come for them. If you just took the action and dialogue, it would make a very short scene. But Arya worries for her master. She considers her reaction. She filters what is going on through her POV.
In short, I write a skeleton first, then fill in, flesh out, etc.
I am not, in any way, an expert on martial arts, swordplay or fighting. I describe things the best I can (and reading other works is helpful). Most authors don't write in technical terms like, "I lunge perfectly with this X maneuver and then do Y maneuver in a perfect twirl" and that sort of thing. Fight scenes can be lumbering, violent, chaotic.
I do have a friend or two look it over to make sure it looks okay, one that has some experience with weapons to make sure logistics aren't embarrassing.