You want Seal of Scaling Health instead of regular health regen is because at level 5 the scaling health regen surpasses the non-scaling seals.

I like to rush the Eye of the Oasis along with the Lonian Boots of Lucidity
- reason being, i like to have that early ward ability, that HP5, MP5, and cool down reduction

Next i like to get Rod of Ages
- reason behind this is for obvious reasons of the 10 min it takes to max out the stats.
- the reason i get Rod of Ages is because of the sustain it gives while leveling up with the passive health and mana regain upon level. But also it gives everything that Soraka needs for her HPS kit.

Warmog's Armor!!!!!!!
- Once i complete this item, the game typically ends soon after. Either the other team /FF
or we just push a team fight and win.
- at level 14-16 my HP5 is anywhere from 500-600, meaning, as soon as i heal someone, my health is at 100% again instantly.
- You can literally heal your ADC tanking a tower until the tower is down and be back at 100% health in less than 5 seconds.
- Having Perseverance mixed with Warmog's Armor at level 15 puts your HP5 under 25% health at 900-1200 HP5 range.

If the game continues past mid game into late game, depending on the composition of the other team I get a Spirit Visage or a Rylai's Scepter

Landing Soraka's Q can be... tricky! Reason being, its slow, its animated, and mid ranged at best.
To help with landing this i have a couple of tricks.
1. Wait for your adc to throw down a CC makes this easy to land
- please note, that you are supposed to try and poke and or harass the other team. I am all for harassment, however, Soraka is not the best at this. You dont want to waste her Q for poke or harass. I recommend using Q when you need to do it.

2. Wait for the other team to engage!
- When the other team is coming at you, you know where they will be walking.
And in all reality, they will not care about some low damage Soraka Q poke. Making it easy to land and or predict where they will be moving.

3. Hide in bushes
- Landing any skill shot from the bushes is naturally easier.