Follow these cheap yet effective tips and you'll do fine.

Summoner Spells: Heal and Clarity - No exceptions.
Loadout at Start is Wards, Potions and a Necklace (as shown) - No exceptions.
Stay in battle as long as possible for alot of gold.
Set up your abilities as shown, it works, and you'll hardly die.
Masteries must be set as is, make no other adjustments.
Runes as is, make sure you have the ones shown or ones of a lower tier.

Pros:

Quick and reliable, tested time and time again. Works every time.
Bots are usually pretty stupid, so you need something to heal your teammates and support quickly.

Cons:

This kinda sucks in PVP. sadly. Bots of Beginner to Intermediate games only.
You can use in PVP, but I can not promise complete success.

You don't need to worry about killing Minions with your abilities. Let your partner do all the work. Sure, fling a moon at the minions if you're bored, but all you need to do is farm and wait for your gold to raise while you spam heal and mana restore your ally.

Always be BEHIND your ally. Don't go to the side, don't go to the front. You're a squishy cleric, so act like it.

You want to be sure you use your potions on yourself often.

Use your summoner abilities if you're and/or your ally are getting halfway health or mana.

You'll be leveling and too busy healing and watching out for everyone that you won't notice your gold until the game is halfway to nearly over, and that's when you buy all the stuff above and keep repeating your heals and such as before.

Silence is key to this build. You're Soraka, tell those enemy champs to STFU.