Find out what a support excels in and focus on it throughout a game. Really just pay attention to it and you'll learn a lot that way.
Like pay close attention to where your creep equilibrium ends up in lane when you play lich and you'll be able to transfer some of that into other games where it still matters a lot.
Ancient Apparition will teach you a lot about map awareness. Warlock and Tidehunter, teamfights and positioning. Lion, Crystal Maiden, Earthshaker, Vengeful Spirit will teach you a lot about stuns and disables and when you might be able to get a kill and when not (which is an important skill to recognize and you'd be amazed how bad some people are at it). It goes on and on, but in the beginning I think focusing on one thing at a time in a game really helps preventing you from being overwhelmed and eventually makes you a very well rounded player.