I was in ur shoes a few months ago, I was also stuck in plat two for a long time, but two most important factors that helped me got out was attitude and focus. By attitude I mean that u should be positive in ur games. Never rage at teammates, if they make a mistake, let it go and move on, if they get a kill or did something well, say gj or something. Keep ur team's morale high. Next is focus, u should always be very aware of everything in the game, literally analyze everything. Ask urself what are the strengh and weakness of ur team comp, what items are enemies building, who's fed, what items are enemies building, when's dragon, whens baron, and how can u press ur advantage. Communicate with ur team on grabbing objectives. There are a lot of things u needa watch out for, that's why u really need to focus to play at ur maximum potential, also keep in mind that this game isn't only about u, ur teammates are also essential to ur victory