Well this is a Soraka Guide and this is how I run it during games.

Pros:
+You can deal quite a good amount of damage with Starcall and Infuse
+You can kite easily with Infuse/Starcall
+Does extremely well late game

Cons:
-People will most likely target you first just because you are a Support
-Squishy early game, and weak heals during early game

E=Q>W R (which is situational)
R is situational because you use it when you need that extra health to gain that extra advantage in a battle.