Get rid of premades. Seriously.
Honestly, I understand the idea of teams and premades. I'm an extremely casual player, but I get it.
However, in blind pick... which is where I primarily play to practice and learn this game better... there are countless groups of 3 or 4 people belonging to the same "team". It's absurd. And it's unfair.
They tend to have an automatic planned advantage and communication is better too. Honestly, get rid of it. Even just in blind pick. It ruins the gameplay completely AND it promotes toxic behavior, as 9/10 times they hype eachother up when something goes wrong.