Soraka is a beautiful Champion. She gives health for you to gain health, can be the difference between life and death, and can, with the right runes, build, and spells, be unstoppable.
My guide to Soraka is not a pro-gamer guide. This guide is how I personally play, and is a guide that I love and thought to share! All of my information is spread out in the NOTES in each section.
Anything in any section can be altered or changed if you want to make this build/guide your own, and i'm totally open to that! For example, I will give you alternative options for some runes or items if you read closer into the notes. All of these are recommendations based on my playstyle and experience. No, I am not a platinum player, but I do have fun, and I tend to do relatively well in doing so!

General:
Spells: Heal, Flash
Runes: Sorcery Primary, Resolve Secondary
Items (first three): Eye of Ascension, Boots of Lucidity, Redemption [optional/situational cores explained in the respective section)
Abilities: Max Q first, then either E or W dependent on the situation.

General Soraka Support Tips:
I'll be posting a general support guide soon, so If I don't go too much into detail here, it's probably there. Always have a ward available, try not to use both of your warding trinkets at once (unless you have spares from your finished support item). Try not to be on the front lines. You are squishy. You will die. Try to stay within [W] heal range to your ADC or (if late game) team to keep them in top shape if a team fight should arise.
Don't spam your ultimate [R] just because you have it. Save it for either early game when you are about to die yourself, or if your teammates are getting lower...and lower...and lower.
Always aim to put your [Q] where they're going, not where they are. It will miss if you don't calculate your enemy's path. If you can, make them go towards where you will put your [Q] with your [E], like a trap of sorts.
Aim your [E] either on them (if your aim is to silence them) or right next to them to get them to go where you want to throw your [Q]
Save your [W]. I know it'll be an instinct to heal whenever your ADC loses even a tiny bit of health. DON'T. Take in the fact that they have health regeneration, and as long as they don't dive in without you, they should be fine.
Communicate! Pings are useful. If you don't have time to type, simply put that you're on your way to drake pit after you CTRL+CLICK your ward. That way, your team doesn't think you're going in to take drag, rather, you're going to ward drag.

If you have any questions, please feel free to comment or message! If you like this guide and want to see more guides on my personal playstyle, give this guide a like!

Have Fun!