How to get from bronze to plat
Step 1.
Stick to 1 role in ranked and only play that role. The more roles you play the longer it is for you to get better at said role.
Step 2.
Limit champion pool to 1 or 2 different champions. Play the SHIT out of 1-2 champions all season, doesn't matter what champ it is, don't worry about counter picking, or whatever. Play your best champion all the time. You're not in the LCS and challenger, so just play 1 champ.. master it mechanically, when you feel like you have (after hundreds of games on that champ) you can start doing that with another champ, knowing you can always go back to that.
Step 3.
Don't solo queue, find a good duo or trio that you know doesn't suck, and only play ranked with them. Solo queue is like rolling the dice on your teammates.
Step 4.
Learn to dodge. If you look up your mid laner and he's lost 10 of his last 12 games with a shitty record, chances are I would dodge. Also, dodge if there are high skill cap champions, like Lee Sin or Kalista or something.
Step 5.
Keep positive. As long as you're winning 3/5 games, you'll climb. Follow my steps, and don't tilt and you will climb in no time.