I started playing ranked a while ago, started all the way from the bottom of Iron. Currently in Bronze 2 and i think i am climbing pretty well with minor setbacks here and there, e.g losing promos. As a Bronzie myself, i noticed that i started climbing better when i changed my mentality. Positive thinking, believing in your skill but still being able to see your mistakes. Be polite to the team and keep it together. Make your team think they can do it, even though they are braindead. I can't even count the number of games i won because i made my supp think that he is good. Tell someone he is doing a good job, and he will actually start hearing you out.
Another way to make people listen to you is carry the game of course. Dont want your adc to feed? become the adc as an example.
I main mid and bot and these few things helped me alot with my ranking.
I will add you so we can duoQ sometime.