Current Build (Notes)
End Build Seal
Probably the safest and most successful build I've seen on here. 200+ ranked solo queue games as Raka for season 6. IGN: Giräffe
After the recent nerf to Soraka it isn't very viable to max anything other than W, but you still start Q for the stronger level 1. Throwing a Q every couple seconds is a lot better than healing for a small amount every 8seconds.
The Masteries are honestly pretty set in stone.
Wanderer to get to teammates quicker when out of combat.
Secret stash for the biscuits, but if you plan on going coin and refillable Runic Affinity is good instead.
Meditation for the mana regen to keep up with the health regen.
Bandit. I see other people not using bandit and it's tilting. Bandit is a great gold income for early lane trades and it helps you get your key items that much quicker. A typical trade early would be a landed Q with auto attacks. Getting both gold from spellthiefs and bandit.
Intelligence and Windspeakers because they are the obvious support choices. More CDR and stronger heals.
Recovery for the extra health regen to go along with your runes.
Tough Skin Makes trading with the opposing support early really easy for you. With the health regen from your Q you easily stay full health after the trade.
Runic Armor The obvious healing from your ult, redemption and Q. Plus the shield from locket.
Insight Having your summoner spells up more frequently increases your survivability. Plus with Ionian Boots that total cooldown shortens a ton.