Hello all this is ImaFirnMahLazr and this is my first and foremost guide on how to dominate with Soraka the starchild, enjoy.
BATTLERAKA ENGAGE.

For runes i take:
Greater Quintessence of Potency: Gives you an AP edge.
Greater Mark of Insight: Adds some extra spam damage of your Q.
Greater Seal of Potency: Nice amount of AP for early game.
Greater Glyph of Potency: ^
Alternatives:
Greater Quintessence of Insight: Stacks with the debuff of Q.
Greater Quintessence of Swiftness: Gives you a good amount of move speed to chase/get away/harass.
Greater Quintessence of Fortitude: Tanky early game

Greater Seal of Clarity: Mana regen is good but since you have Infuse other runes will help you more than this.
Greater Seal of Resilience: Generally harder to kill.

Greater Glyph of Shielding: ^ Helps out survivability early lane phase.
Greater Glyph of Focus: CD reduction is huge on soraka, it allows you to spam your Q every mother f***ing second.

Self explanatory, i won't go into further detail.

Pros:
+Soraka don't give a **** about n00bs.
+spammable ability that does heaps of damage.
+Very good survivability.
+Extremely versatile champion, support, carry, tank, you name it Soraka conquers it.

Cons:
-targeted.
-ignite rapes her early game.
-is equal to a bag of **** with legs early game.

Good:
Ghost
Flash
Exhaust
Teleport
Cleanse
Clarity
Clairvoyance
Revive

Bad:
Garrison
Fortify
Heal
Rally
Promote
Surge
Smite

Here goes the order from most important to least totally depending on what you want to do
support: R>W>Q>E
carry: R>Q>E>W

Doran's ring: Good early game survivability + a solid amount of AP
Sorcerer's boots: Rush these because stack with your Q's debuff and do an immense amount of damage.
Aegis of the Legion: Awesome survivability you are practically unkillable with your phat horse heals.
Mejai's Soulstealer: This is a key item that will make or break you, This determines a good Soraka from a bad Soraka, This is where your ulti comes in handy. Every team fight pop it about halfway through, if you don't get any kills or assist's, but when you heal somebody and they get a kill you get an assist. even if you didn't touch the person that died. If you suck and can't get any stacks it's useless so just buy an Abyssal Sceptre.
Soul Shroud: This is another key item in which is provide you with some health and CD reduction + the buff for your team.
Rylai's Crystal Sceptre: Once obtained you will be a BOSS total indestructible and your abilities will hit like a flying toaster from hell.
Guardian Angel: This is the last item you would get, it provides you with armor and magic resist, along with the nice little 2nd life. This is when you can be extremely aggressive and use your character to the fullest extent.

I hope you have as much fun with "Battleraka" as i do when i play her, this isn't supposed to be a pro guide i'm just showing you my thoughts and play style of this mythical beast. I hope you all have a nice day and **** **** up, Good day-ImaFirnMahLazr.
BATTLERAKA DIS-ENGAGE.