It’s helpful to get some basic library assets so you have a few ready-made options you can try out, use, or blend with your own recordings. While it’s ultimately down to “personal taste,” which is difficult to define, here’s what I think about when approaching a fight scene:
What’s my reaction, as the audience, supposed to be when people get hit?
Unless you’re a very grounded drama (with little fighting) or a very realistic sports film (like say a biopic about a boxer with a documentary feel), you’re probably going to be exaggerating things a lot. Even movies with “gritty” fight scenes have absolutely ridiculous whooshes and hits (see this scene for an example).
I personally feel that violence, in the repulsive, painful sense, is all about the details, not how big it is. If you’re going for a lighter-hearted tone, it’s okay to have big, ridiculous smacks and thuds when people get hit; this actually can help the violence seem less serious. For grittier fighting, I actually tend to tone back the hits to more clothy-feeling thuds, and watermelon smacks can work well for face hits in this kind of film. You’ll notice the few “violent” hits in the Kingsman short (the bone breaks) have extra cracks and pops in them so they feel a little more “harsh” than the other hits.
What subgenre is the fight scene?
While it may sound weird, whooshes can really date a fight scene. Fights up through the mid-90’s often had very vocal-like, mid-range whooshes. The Matrix influenced a trend of equally tonal whooshes, but with a more fluid, watery quality, where the whooshes are long, dynamic sounds that flow around the strikes. I feel like more modern/gritty films overall favor shorter, snappier whooshes that are less mid-range and feel more like cloth snaps. If you’re doing a genre parody, definitely look at references to figure out what’s been done - getting the sound right can subliminally add a lot towards nailing a tone.
For Rocket Jump videos, I typically go for a “modern with a whimsical flair” approach. While all my sounds in the Kingsman scene are exaggerated (to make the scene more dynamic, exciting and cinematic), the whooshes are fairly cloth-heavy (except when Freddie does the “come here” gesture - which I chose to instead play more as a “martial arts parody” with older-sounding whooshes). While the hits are huge, they’re less goofy than old-school martial arts “KA-POW” sounds. I felt that when blows are being traded, the fight is supposed to be “cool” - while there’s humorous use of the umbrella, the hits themselves aren’t supposed to be funny, so I made sure they had some edge to them. The comic moments (like the banana peels) were treated differently, and I used more “conventional” cartoon noises like slide whistles and big splats to emphasize the goofiness.
While I try to game plan in advance when I’m selecting my samples for a project, some of it also comes from experimentation. If you edit something and you’re not sure, try out any other ideas you may have, and compare them. If you have trouble deciding, sometimes taking a short break and coming back can really refresh your perspective, too.
I feel like this got super-rambly, so feel free to hit me back with more questions or things you’d like me to elaborate on! Writing words about sound is tricky, so let me know if I missed part of your question or was unclear.