Not Updated For Current Season
Soraka is an extremely handy teammate, if played well you will rarely ever lose a match provided your team knows what they are doing and communicates well. She is, in my opinion, the best healer in the game with her ability to heal single teammates, restore mana, and use her ultimate which heals your entire team for a very large amount of health.
This build is what I find myself using nearly every match when I play Soraka. Very rarely do I deviate from the build I've put together, but it's a build so feel free to deviate all you please.
The effectiveness of Soraka's heals are very dependent upon having plenty of AP. They'll work without AP, but you'll notice a big difference in your healing with more of it - hence the "Force" runes.
The quints can be whatever you please, I prefer the XP boost with the "Wisdom" quints but you can substitute for CDR or AP if you please.
I start with Amplifying Tome and lane until I have enough to go straight to Morello's Evil Tome because with Soraka you can lane nonstop if you aren't being harassed too bad. From Morello's I grab Ion boots then spirit visage, this will bring you to 35% CDR - 5% away from the cap of 40%.
This is usually as far as I get into the build before we win or the other team surrenders.
If you can get to it, Rylai's Crystal Scepter will give you 500hp. This is rare for me but the 500hp will be a great boost to your low health pool which sits around 1800 or so at 18.
The Rabadon's Deathcaps will give you a ton of AP which scales extremely well with Wish's 1.3 AP coefficient.
Now, in the event you can acquire every item on the list, your wish will be healing for ~1122 HP in one cast and your heal will be healing for ~825.
First we take Infuse, a costless spell that silences an hurts the enemy when they're targeted or returns mana to you and your selected ally. Take care not to cast it on minions and always use the self cast key (Default left Alt) if you intend on using it on yourself.
Also a great early game harassing skill.
Infuse is a key to success, it in part with Astral Blessing allows you to stay in lane until you feel like recalling, never neglect its usefulness.
Astral Blessing starts out healing pretty low, about 60-80 hp. By rank 5 its base heal will be 300 - a good chunk of hp that will save your life as well as countless teammates if timed right. I always use the "On Mouseover" button to cast this (Default left Shift), just hold down shift and press the button and it's cast in comparison to press + click.
Watch Wish's CD, when it's up look at the frames for your teammates on the left side of your screen. If you see any low (my personal rule is 2 or more allies with AT LEAST ~20% of their health gone) cast it. I also use it to save my own end, it's a great emergency tool.
To sum it all up, this is how I play Soraka and do well with her. Short timers on Astral Blessing and Infuse allow me to keep my mana filled to the brim while doing the same for my teammates health.
I forgot to add - DO NOT SOLO WITH SORAKA
You will be ripped in two, stay behind the minions and your laning partner. If you have a good laning partner like I do, you can ask them to hit minions low so you can last hit for the gold as Soraka has a very hard time getting gold. Don't risk dying to an opposing champion because you wanted to get a kill. Soraka requires a lot of patience and quick fingers.
Good luck to all you Soraka's, new and old!
Also I would like to give credit to Paelidore! His Soraka build is the basis of mine and the reason I started playing Soraka.
His build can be found Here