Ranked going terribly

The past few mounths, i've been on a huge losing streak in ranked. In normals though, i do pretty well. I'm not sure what i am doi ng wrong here. I never flame my team, EVER. When i have a stratergy to win my teamates never listen to me, even though i try hard. I get it. this game is difficult but what can i do to improve myself? Plz respond i am desperate.