I used to play support Janna... Those were dark times... Let me show u the light :)
Theres really not that much too it. shield yourself when u go in for an engage or when u want to farm fast. use your q in the middle of the fight, for example, If you are fighting a riven you want to disrupt her while she does her Q spam. W to engage! W is too good! walking through minions is awesome during fights and the speed on that makes a fancy equation like this. (W passive + regular passive + Q + W = U CANT CATCH MEEE *****)

push lane BBY. you can escape from ganks easily! Remember! ULTIMATE HEALS LIKE A BIG PIECE OF POOP!!!! IT SUCKS ***! But! the knock back is soo good! if you want to be a jesus swag janna, flash behind them and then ult.. (it sounds cool but it never really works (UNLESS U ARE JESUS!))
Yeh... thats about it <3 I love you all.