Any tips for getting out of plat?

I have been trapped in the elo hell known as plat for a couple weeks now I'll go on 3-4 game win streaks then go on a 4 game losing streak and end up right where I started I've tried group posts as a tank and it always feels like I am doing everything I can every game and I'll still lose I've spent hours in practice range working on my accuracy combos etc but I still don't rank up is there something I'm missing here?