Hi guys,
lets see, what can i give for you! :)
First Rule, don't attack the enemies, but you can kill minions.
Everytime, stay back, behind your partner, and heal him/her, if him hp are below 80%.
If your partner dying or teleporting back to the base, go back to the tower, and stay there, don't try to be a hero :D You are a support type, so you need to feed your partner, not yourself. If too much minions coming to the tower, you can attack them with "Starcall", but let the tower to kill the enemie champions, don't attack them.
If you and your partner going to push, stay at the max. ability range, so you not give a chance to kill you, and follow your partner movements. When you got your ultimate skill, use it, if you see your partners going to push, or confront the enemies. Don't worrie, if you healing, and supporting, you can get enough exp, cause of assist.
The best partner for Soraka is Ashe, and Caitlyn, and be carfull for tank or fighter partners, cause they need to go close the enemies.

Thank you for visit my first champion build post, and i hope, it will be helpful for you.

And sorry my terrible english xD

Kind regards,
Ashline