You can’t just stay away from openings. If you’re playing White in particular you’re opponent can choose to play sanrensei Chinese kobayashi etc. I don’t think you can prevent these openings even without studying them some amount.
Joseki are definitely handy when playing stronger player who probably know some joseki. Managing to stay even for a while into the middle game has to be better than being behind against a stronger player in the middle/endgame.
I could probably remember a couple of things that made me improve over the ranks.
-TPK learning how to block off your territory, whether it’s simple endgame like when to hane on the first line or not, or just backing off a bit from opponents stones.
-DDK Some simple 3-3, 4-4, 3-4 joseki, it kind of has to include pincers because you sometimes can’t choose whether an opponent pincers or not. It’s not easy to decide though when to pincer or not, even ai have probably questioned traditional pincers. Basically if you can get a semi even result in a corner you can move onto the rest of the game - there’s lots more game to go and practice and learn!
-DDK A huge thing that helps when trying to rank up is learning (asking yourself) when to play away, do I need to answer my opponents move? What can they do if they got two moves in a row here and is that important or not. It’s a hard question but stronger players can help and to an extent ai but they even tenuki too much for my SDK comfort 
-DDK being aware of different haengma is also a plus. Just thinking of bamboo joints, table shapes different types of jumps and connections. I know someone recommended Dsauns shape lecture to me and it was interesting to be aware of some good and bad shapes and drawbacks to some shapes.
I usually like learning from books and YouTube videos but that might not suit everyone. But I could link a bunch of things.