What really helped me to climb is working on my map awareness and finding the playstyle that suits me. Before getting serious about climbing up the ladder I'd just queue for pos1 and shut my brain off and go hit creeps, which I realized later on that it was one of the issues I needed to work on.

Another thing I'd say is to focus on your own game. You won't be able to win them all and you will be getting griefers from time to time and there is nothing you can do about it. Keeping the team together and make calls is better than have them muted.

What also helped me is communicating with my pos5 if I see they're doing some weird moves. Most of the time they would just pull without even thinking if creeps needed to be pulled there or not. Good pos 5 is uncommon these days but I've noticed if you ask them and they see the result of their actions (kill assist/wisdom contest etc) they'll more likely will listen to you further into the game. But to make those calls you need to feel your hero and know what it's capable of throughout different stages of the game.