First off Tank Sona may sound ******ed. But Sona is the main character I play and she flat out ownz this way. Start off with Mana Manipulator. This item helps you and your teammate lane immensely. If you play aggressive enough and your buddy does the same you should stack up a few kills before lvl 6 and not have to go home often. Then Rush Force of Nature. After Force is built get the other armors to further boost your dankness. Everyone will target you and not be able to kill you. Meanwhile your team and yourself will be constantly getting healed and you can wear down anyone in team fights.

I have found this combo of runes to be perfect for Sona. It gives her a little more bite with the AP and further boosts her Armor a bit.

Pretty basic 9 0 21. Make sure to get Summoner's Insight since you will be using both Heal and Clarity Spells.

Mana Manipulator for early lanning sustainability. Boots to make ya quick and get better cooldown. Then rush Force of Nature and the other fun armors to complete the Tank Goodness.

I start with W "Heal" first just to help my teammate off a little earlier. Then I alternate that with Q "Damage" until lvl 6 when I get my Ultimate. Her E is nice to spam but doesn't help much honestly. Her most important skills are Q and W and the ult. So Max them in that order first Q+W then R!

Heal and Clarity. Full on support and lane sustainability. Don't get anything else. You are all about helping others! No need to Run or Flash, you are Tank Sona.

Pros:
If you play aggressive and have a good team that does the same you will OWN. They will think you are the easy kill and focus you. Then let your teammates wear them down while you heal everyone.
Cons:
Takes a bit of time to get the items up. You don't have much escape, but if you play like a Boss that shouldn't matter. Ive gone 10/4/34 with her before. Pure Ownage that nobody expects!