I'm in low Silver because of the pre-season ranking drop and the fact I didn't know the game well. My personal way of leading a team is just to have them focus around the fed member. Like, say I was a fed Jinx, all the team would have to do is keep me in a good position to win most teamfights, then we could push down the towers pretty easily. It's not always guaranteed to work. For instance, a ranked game two days ago had our team 8 to 18 or some pretty high figure. I had all 8 kills (mostly on accident) but we couldn't get the team to play around me for the win. Also it's not all about the team play, we all make a bunch of mistakes too.
Also, people in this elo don't generally want to learn how the roles work. So, it's going to be a lot harder to carry as a support (not saying it's impossible). If you want, we could duo some time. My name is Bushi Chan on League.