Playing ranked right when you hit 30, rookie mistake xd
Although I can't help you with your mechanics and game knowledge, here are a few tips from someone who was in your exact situation last year:
-If you're going to play support, trust your team
-Don't flame, just makes it worse and will make you feel like sh*t after the match ends
-Treat ranked as just another queue, don't overthink it
-Play more, you'll get the hang of it and you'll start climbing.
-Don't expect a lot from your team, since you're most likely going to be placed Bronze-Silver
Just a side note, practice in Ranked 5v5 flex, and never play normals (unless you're going to play just for fun). I'll probably get some hate for this, but trust me, it'll prepare you for ranked more than a simple normal match.
Once you start winning in ranked, you'll get addicted and the feeling of a win gets better as you progress.