I can play only in public rooms so basically that's my experience and my way to have a quite game with no annoying people ruining the match.
First create a public room, choose your settings.
The main part is the hardest: have patience. Take your time to vote and join the debate even if people voted randomly(ask why). Kick cheaters and toxic people. Remember for next match who lies just for fun even if they are not the impostor to have others get voted.
Encourage members to do tasks, dead or alive.
It's hard, but do not leave the game!
As soon the game is finished click play again to continue to be the host. When people rejoin a "gg" is always accepted.
It may take several matches, but you will surely find those who want to play in peace without annoying people calling emergency saying "blue was too close to me so is the impostor". 99% will be difficult to reach 10/10 of good players, but even with 5 or 6 good ones the others have to stay at rules or leave(avoiding to lose game for mass quitting).
I think I wrote all, probably obvious things. The developers are going to add a friend system but in meantime this could improve the game experience. As least helped me.