Sona is my favorite supports because of her multiple aura abilities, i just spamed them in team fights, her Q is boss, knowing the difference between someone's basic attacks with and without her.
Soraka is the "best" in my opinion since her skills either act as support or dmg, can't go wrong with AP Soraka.
I started with Annie(her Q is OP for minion kills) gives a basic understanding of Passives and how to manage it( can be tough though when you want a stun and your 3 spells away with no mana)
Then Teemo one of the best harassers because of his ever lasting E, hit them once and they fear you for a while, and wont approach with a quarter health left, cuz as long as you hit them while they are killing you, you get a kill 2 b/c poison ftw
Then I just played with all the free characters, to learn all the roles that they could run and what not. which also gives you better Item knowledge instead of just AP/AD/Tank items.
Hit lvl 30 and i run the world with Ezreal, Fizz, Talon, and Cho'gath(just watching him grow is the best feeling).
and remember most CC(crowd control:Silence/blind/stun/poison) champs get rather irrating to other champs. Darius is not OP, hello silence.