Pros
Amazing support. (heals, dmg increase, chase/escape)
Super mobile / built in escape
Late game amazing support
Opponents misjudge Sona for support, giving you easy kill opportunities
Good looking champ
Can do your game (if you play with noobs)

Cons
Squishy
Gets focused by smart teams

Always look to save your team mates with heal or speed them

In team fights always stay at the back and heal you should get the 1st and the 2nd aura up so you give def and attack. Sona is usually focused (by the smart people) so be carefull if they focus you just flash and heal.Here is my best score 8-2-42
(http://www.gravatar.com/avatar/2f085eef80d07ad8f0ee32c1c7f9e20b.png).If your team mates want you to go middle don't accept Sona needs a partner.

Use clearvoyance from the early game to watch for ambushes.For flash, use it when you are low health or they focus you usually i flash throw walls then speed with 3rd aura and back to heal.

Place the Sight Ward when the minions start fighting there is no point to place it earlier because it's time will be gone by then.I get these boots because with them you can easy escape and easy go on time to heal your teammate who is on 300hp.The Arch Angel staff gives you lots of mana and AP.The Soul Shroud gives your teammates buffs . The Shurelya's Reverie help you escape if your 3rd magic is in cooldown.Well,Rabadon Head ,you know what it does.Does sick HEAL!!!

If you are heaving hard time you should up the heal 2 times not the damage skill (when you are playing against dps ranged or sth like that).If you play against tanks up the skill as I said.

Well, for that

NEVER JUNGLE!