Feel stuck in the same plastic or wood division? No worries, I've been there too. You are not alone in this troll horror type of a thing that is called ranked game in low elo. This is how I became better at League and, of course, I am going to tell you why.
1. I played only three champions on three different roles. If you don't master at least three champions on at least three different champions, don't play ranked, because if you get autofilled, what would you do then? Ruin your game? Stay away until you master those three roles. I play Sona, Miss Fortune and Ahri, that means: support, adc and mid. Check my Sona guide.
2. If someone bothers you or types too much, mute that person. This game is too intense and few seconds can lose you a game. Focus on the game, not on chat. You are not allowed to type more than three words.
3. Congratulate your team for what they achieve: a kill, a dragon, a flash from the enemy. You would be surprised how much impact positivity has during the game.
4. Try and focus on objectives, kills cannot bring you automatically a win. Since s8, during late game, their team can catch back on gold, and if their turrets are still up, the game can change its couse with few team fights.
Good luck, guys!
Rami