Well this is my first build putting up here.. so go easy on me. First of all Sona is a great champion and lots of people underestimate her, but she is alot more powerful then you think.

I love to start her off in mid and the reason why is to level her up as fast as possible. Since they Nerfed her early game damage its best to level her up faster to get that great damage with her Q. always try to build up your passive against your enemies to get that great lane dominance. its also great to take flash and ignite to do a great combo that I think its 10X better then Annie's. which is get them to half health, then stand still until they get close enough for you to flash in ult them, Q them, and then passive + ignite. which will be a guaranteed kill.

That's why I went with flat ap runes, magic pen runes, and mana regen per level to regenerate faster since your mid. Most people don't think Sona mid is a good idea but once you've experienced that thrill of being able to dominate your enemies you will always want to play Sona.

Pros
*good dmg
*aoe stun
*good escape with celerity/flash
*heals
*big tits

Cons

*squishy
*gets focused
*is sorta slow without celerity

First of all I take magic pen marks because its good for later game when everyone has so much mr. Then the flat ap glyphs are for early aggresiveness. The mana per/level seals are good that way you can buy boots like I do and not having to worry so much about mana, and finally the ap per/level Quints are good for late game dmg.

My first item that I always choose is boots, yes I know no dmg, but boots are good to harras with. you have a nice speed to get close enough for you to use your q and back off right away which will make it seem like you have a ridiculous range on her Q and you get to dmg them before they do anything, its also good for getting away faster, rather then being slow with a dorans or meki pendant.the 2 hp pots and 1 mana pot is for longer lane dominance. after I get 1000 gold I always go back to base to get my tear of the goddess to keep building up its passive and for the extra mana and mana regen. Then afterwards I finish my archangels and head into a mejais for that extra ap you will be getting from assists and kills if your good like me :D. Grabbing a sheen afterwards is perfect for that gigantic dmg boost from your passive and the sheen proc, usually the sheen and your passive will take away any ashe's hp by half, which usually all you have to do is ult and the rest is common sense and she will die instantly. everything else is self explanatory.

These are some of the games that I play with the same build