I recommend FLASH as this spell can allow Sona to get out of,erm,not a really tight situation where she is being attacked.I recommend Clarity as this can allow her to stay on her lane with her partner longer as she has a Mana Replenishment at hand in case she runs low on Mana inn her lane.You might be thinking of taking Clairvoyance up as a support summoner spell instead,but I strongly recommend Clarity over Clairvoyance.

Start off with Mana Manipulator and you can choose between a Sight Ward or two Health Potions.When you have enough gold for a MERCURY'S TREADS,just RECALL,then buy it.

My Masteries are 9/21/0.I focus more on Defense as this can make Sona a formidable tank and support champion.