Need a teacher

Hey guys, I've been playing for about a year now and I can finish off pvp games at 17/6/20 but as soon as I play ranked I'm getting destroyed. I typically main jinx but I'm looking for a support that can teach me more about how to compete in ranked games. Any help is very much appreciated. Feel free to add Zanderrrrrrr. That is 7 r's if you can't tell lol