I've developed this build through playing as Sona so I know her pretty well. The first problem you face is her mana; If you lane with an AD Ranged carry or Melee carry, you will notice your mana runs out pretty quickly because you will be healing your partner a bunch. This is solved by runes, masteries and early mana pots. Next you will find that you are pretty squishy and slow, stay back, hang in the bushes, don't farm, and heal your team. Don't forget that your heal is used on you and the nearest wounded ally. If you get caught in a lane by yourself and you are pushing, go back to the turret and hug it if you are worried about a gank.

Masteries are a no-brainer. With basically any support you are going regen, cool-down reduction, and gold production. Put most points in Utility and your spares in Defense.

Your runes are basically laning tools in this build; CDR, Regen, Gold production so you can let your partner farm and get fed, and your basic armors.

If you know the other team has a jungler (Common in Draft Pick and uncommon in Blind Pick), you should go Clairvoyance. For lane sustain, you should get heal; it helps in teamfights, sustaining your lane partner, and saving lives. If you are not confident in your ability to get away, grab flash in place of heal, that can save your life and position you correctly for your ult.

You get support/team need items ofc as you are the SUPPORT. You have regen runes and masteries so your pots should last a while, if not you can put some items off to get more.

This build is still a bit raw and I would love your feedback... please don't troll, I have no lame excuses it's just annoying. Thanks.

Farming with a support is pretty simple- DON'T DO IT! The only time you should be farming is when the whole enemy team is dead and there are minions on your turrets, kill them to defend your base and don't throw the game by taking CS from your carries!

While in mid-game, stay with your team. You are the support, ward, heal, defend. Your job isn't to tank or attack but simply to keep your team alive. With Sona, spam your E and W instead of your Q and W, you're team doesn't need your extra dps they have enough, what they don't have is heals.

Depending on your lane, you will usually want to rank your heals first. If you lane with a melee carry, get heal as they will be in the fray a lot. As for ranged carry, you can rank you q more than normal as they won't be getting harassed as much.