This is my own opinion so you dont need to agree from what i say cuz this made me climb the ladder in season 5
I started off in Silver 3
Back then, i mained adc. with Quinn (old quinn, not the new one). i went duo with my best friend and we won like 80% of our games together. ( we skyped a lot too and pre-made bot in silver is easy to carry cuz they focus the tanks anyways)
After some climbing with my friend, i started to solo in Gold 5 because he liked to troll more in ranked ( Not playing so serious ) and i liked to climb really fast so we decided to split up.
So from gold 5 to gold 3 i mained jinx, really. that champion in season 5! she was so easy to climb the ladder cuz i couldn't climb it anymore with quinn.
And she was so strong at that moment.
From gold 3, they started to focus the adc. so mostly, you get blown up by an assassin. so i thought, let me main mid now.
And it was unbelieveable how fast i climbed the ladder, from gold 3 to Diamond 5.
My goal was Diamond 5. i was so happy that i finally reached my goal. And after that, i quitted ranked cuz i reached my goal.
Maybe this year, i might go for master or challenger^^ but who knows:p
tl'dr duo with someone like mid and jungle and let him camp you until you get fed and then **roam **alot. to help your teammates out