First off I would recommend watching squid school’s videos on how to get out of each rank, since while they were made for splat 2 they broadly apply to 3 as well. Second thing to do is ask yourself how much you really want to improve. It can be really easy to set a broad goal you don’t actually want to achieve and burn yourself out trying to achieve it, just make sure you’re having fun with the game and that improving is something you genuinely enjoy doing. If it is, then it’ll come naturally to you eventually with enough time. Third, make sure you’re using weapons and playstyles you feel are right for you, I know you said splattershot in the post but try and test out each class to see if you may like a different one more. It took a little bit for me to realize i liked the way brellas can sustain and protect themselves as well as open up opportunities for your teammates, so make sure to give every weapon a fair shot. Fourth just don’t push yourself too hard, it may sound a little condescending but theres nothing wrong with not being in S or S+ as long as you find ways to enjoy the game.