What makes a good support player?

Hello my name is vac, and I'm around 1k mmr. I find myself supporting 90% of the time and was wondering what makes a good support player? Like yea I can stack and pull and ward, but how do I do it better? Like what separates a pro support from a scrub like me? And yea I get they have better map awareness and can mechanically play better then me, but yea, what could I do better?