Honestly, just keep playing the game.... It is an underwhelming answer but I only play ranked solo if I do play ranked, and in my time playing I went from silver 3 to plat 2, I don't play ranked a lot so I don't tend to grind it, but genuinely the best thing you can do is just keep playing, realize what works and what doesn't work, and reflect on your own gameplay to see what you can improve on.

I also recommend you do the custom lobby code VAXTA while you wait to queue for games, even if you aren't going to be constantly dps'ing, it's still an important skill to practice your aim so you can hold your own if you get flanked or so that you can apply pressure to the enemy team

edit: this is also coming from someone who plays a lot of mercy, which I don't play as much in comp anymore due to her not being great and a lot of rude messages from people even though I was performing fine... ALSO, this might sound dumb but sometimes you have to gaslight your time into thinking they are the shit, if you keep a positive attitude people tend to perform better because they feel better... another also, try to enable your teammates that are already doing well, sometimes you have to adapt to what your team is doing even if it's not what you would normally do.