Sona got Nerfed! And items got changed. Will re-evaluate these changes and edit my guide in the coming days accordingly.

Well, the way I play Sona is also a little different than other guides I have seen.
Sona is a great Champion, capable of filling many roles, yet she always seems to get pigeonholed as just a support. On Dominion I have seen people play her AD, yet I do not think that that is making use of her full kit. In my view she is so much more than just support or AD. She is a support plus plus! Since release (some time ago now) she has gone through a few changes. She is now much more dynamic than just a stance dancer (roll face on keyboard) style champ as her new kit means you have much more options when facing enemies. The technical difficulty has gone up, which means she can scale better the more you get to know her.
This guide is about having fun, and trying something different. Comments are much appreciated. Please don't rate without leaving a comment. Thanks!

A quick intro to Sona for those of you just starting out with her.
Sona is a ranged, ability based Champion. She has offensive and defensive capabilities.
She can: burst damage; buff herself and teammates AP and AD; heal herself and teammates; buff herself and teammates armor and magic resist; debuff enemy damage; speed up allies movement speed; slow down enemies movement speed; and even make enemies dance (AOE Stun).
What an awesome kit eh?! Yeah, I thought so too. What's even better is that all her abilities (except her Ultimate) are on a very low cooldown, allowing you to use her full kit most of the time.

I play sona as a hybrid burst damage poker with support functions. What I want from Sona is to be able to deal lots of damage, while still being able to support my team and also not die if I get focused. Sona's kit, with the right items, can do this and do it well.

So, here's what you do. Buy yourself a Sapphire Crystal, an Amplifying Tome and some Boots as well as a Mana Potion and Health Potion. Prime your passive by using your abilities a few times. Depending on your team/enemy team, decide which aura to have active on the way to top. Most of the time I go for the Hymn of Valor aura. Get to top with your team, make sure you're not there first. Do poke and play back and forth up top saving your Aria of Perseverance for a team member or yourself who is about to get burst. Use your summoner heal if necessary. Once you've secured top you should be in a good position to hold it while your team mates go back to base. Try to stay top till you have enough to upgrade to a Sheen and Sorcerer's Shoes. From here on you can rush your Trinity Force starting with a Phage or you can grab Aegis of the Legion first then finish Trinity Force.

Now lets take a break from the build here and focus on some reasoning behind these choices.

Sheen on Sona makes sense. It gives her much needed mana as well as some Ability Power to help her abilities. But the main thing about this is that it helps Sona with her burst. A Hymn of Valor coupled with her Power Chord passive and a Sheen proc deals some good damage. Especially since we will have the close to 30 magic pen from items and runes along with the percentage penetration from masteries and the game mode.

Upgrading to Trinity Force adds some much needed health and attack damage along with some critical hit chance which will help your burst. You also get some movement speed and a slow to help kite as well as a sweet upgrade to the passive from Sheen.

Adding in a Aegis of the Legion provides great defensive stats as well as offensive stats for you and your team mates. It is very gold efficient when you are around team mates.

You now have your base build. You can now help support your team much better, can do much more damage and move around the map very quickly. You also do both types of damage, making harder for the enemy team to defend against.

You want to focus on backing up your team while defending points. Always try and have three points, but only ever go for more points if you have the numbers advantage. By this I mean dont rush their mid point just because you can't see the enemy team members, only ever take their mid or bottom if you have just killed a few of them. Defending points is much easier than taking them.

Sona has great mobility, so the best spot for her is hanging around mid point. As soon as you see a point that needs help, pop your Song of Celerity and bost of the speed point and get to your team. Help save a team mate with Aria of Perseverance, use your Power Chord on the enemy to get the debuff on them or use a Hymn of Valor combined with a Power Chord to burst them down.

A quick tip on Power Chord here. It comes up after three abilities cast, which is perfect for your spell rotation. Depending on what you want to do with your Power Chord, try to NOT start your rotation on the effect you'll want to end up with. So for max damage try: Aria of Perseverance, then Song of Celerity then Hymn of Valor which will engage your Power Chord for a big damage hit. If you wanted to gimp the enemies damage output, start with Hymn of Valor, then Song of Celerity then Aria of Perseverance which will embue your Power Chord with the damage debuff.

Have you noticed sometimes your teams doing really well on Dominion, your at 450, the other team is on 250. Then, after a few deaths on your team, you start loosing badly. Most of the time it is because your team has lost its synchronicity. In their haste after dying, you and your team mates rush to try and regain that lost point. This starts a chain reaction of people going in one by one. This, as you may have deduced, is not good. If this happens, tell your team either by the retreat 'ping' on the mini map or through chat, that they should fall back and wait. If you are the one out of sync, just hang back a bit and farm. Don't rush for the top point that looks undefended, because most likely, 'its a trap!'

So you've got some gold, made some kills and want to buy more gear. What to get... Well, things that would be good: Cooldown reduction, health, mana regen (for more longevity) and more damage!

Depending on how the game is going I get a Soul Shroud, a Nashor's Tooth and a Zeke's Harbinger (In no particular order). These items will round off your build nicely allowing you do much more damage, give even more auras to your team and give you a bit more survivability. The attack speed will help nicely with getting slow procs off of Trinity Force as well as allow you to do more damage since Zeke's Harbinger will now give you some good armor reduction.

You also are now at the cooldown reduction cap of 40%; have over 5300 effective health without your Aria of Perseverance active; have 23% lifesteal; over 140 AD and 99 AP without your Hymn of Valor active; a 15% crit chance; and 419 movement speed.

I hope you liked my mini-guide on how I play Sona. I will update this if it gets any interest from people out there. If you have any questions, please do ask. I'll reply to them.

Have fun playing Sona!