Well, I saw Ahri when I started, which was... around the time Jinx was released? Really can't remember the day I started, just know it was around about then. Anyway, I saw her and really liked her concept so I ended up maining her after someone bought me her, until I then discovered a few other champions and moved on from being an Ahri main. I had no idea what FotM was, or even what the LCS was at that time so I was playing her based on her playstyle and things like that, but then I saw Riven.
Vs. AD mids such as Yasuo or Zed, it's very much advised to get a Zhonyas early to block their damage either completely with the active, or block some of it with the armour it gives. Just another note, vs heavy regen champions such as Swain or Mundo, it can be worth it to invest in a Morellonomicon.