How be diamond

I think the way to rank up is to just play carry roles and win your lane.
You wont get out of bronze supporting. I've been there.
Pick one role which you wanna main, for example ADC.
Then focus on learning. Learn to farm and get ~70cs in 10 minutes.
Learn to harass enemy's when they try to farm. Learn when to use abilities.
Work on getting a good pool of champions to play with for every single lane in case you get autofilled.