Becoming a better player

Im a League player from the end of s2. I never played much till now. That would explain why I'm such a low summoner level of only 26 form time having the account. I main support and am getting close to ranked. What are some supports that do well in rank and how is it best to play them? I currently have Nami, Thresh, Blitz, Zilen, Lux, Morg, and i occasionally suppport with a voli or braum.