I can only speak for myself, but I would venture to say that this list extends to most women's preferences as well. So here are the things that will almost always make me swipe left (and probably most other girls too):
Fish Pictures
This stereotype has persisted through the dating app ages - I remember first noticing the theme on Hot or Not (I feel like I'm aging myself by admitting that I used that app). A large amount of men - especially where I'm from in Missouri - flaunt a rather unremarkable aquatic creature in one or many of their pictures, but holding up a fish is one of the fastest, and surest ways to get me to swipe left.
Hunting Pictures
I almost lumped this in with the fishing pictures but I feel as though this one almost needs an asterisk by it. My problem with hunting pictures is when a guy holds up his kill as a trophy. If you're in hunting gear that's totally fine with me, but I don't regularly choose to look at pictures of dead animals and I certainly don't want to see them on a dating profile.
Exclusively Group Photos
I'm not trying to play guess who and figure out which guy you are. If you exclusively have group pictures, it's probably going to be a no from me.
Not Showing Your Face
I feel like this one should go without saying, but you'd be surprised how many profiles I've come across that do this. Please put up a picture of yourself. No one is on a dating app to look at your memes. Yes you have a cute dog, but that's not what we're here for either, and no we don't want to just see your abs.
Cliché Bios
Having an original bio will increase your chance of matching astronomically. Bios like "I'm only here to makes friends the same way the plumber in porn is there to fix the sink," or "here for a good time, not a long time," (and especially the recently used "if coronavirus doesn't take you out, can I?") Shaking my head at you guys. Come up with something unique and you're more likely to be memorable and have your match start the conversation.
Nothing In Your Bio At All
This one isn't always a deal breaker, but if your bio is completely empty and doesn't have a description, work, or school - it's just blank - a red flag is starting to wave for me.
These are pretty little things you could easily change that could make a big difference, but at the end of the day if they are things you have on your profile that you feel show who you truly are - leave it there. What's most important in dating is to be your authentic self, and if you really are proud of that 4 inch fish you caught - then by all means, show that sucker off.