Hey. Of all support champs that there is Sona is the one that can deal the most damage. She is the best support to use at bot lane because she provides attack damage aura. When you play sona u want to se the bush to hide and harras the enemy.
Summoner spells: Heal and Clarity
Heal is becoming the new meta at bot. Nice to bait the enemy at low lvl. Almost everyone will tell you that CV is a must, but is it? Is it really? If CV was so good why is nobody else getting CV? Why? BECAUSE THERE ARE BETTER SUMMONER SPELLS THAN CV YOU CAN USE! And for Sona that spell is Clarity. Clarity allows you to harras as much as you need to own the lane. It also allows you to heal the damage you will recieve from the aggressive playstyle.
Max Q first, then W. Wait with E untill both Q and W have been maxed. Get ulti offcourse.
Items: Start with ruby crystal. This allows you to play aggressively without worry about dying so much. Then get lvl 1 boots. Then get another ruby crystal. Then get soul shroud.
Then get cooldown boots or magic penetration boots. Cooldown boots is what I prefer.
The best item to get for the team is Will Of The Ancient. If you need mana I recommend you get Sheen. If you like to harras alot Sheen is nice. If you like to stay in the back I would get Will Of The Ancient. After this you can get whatever items you feel like you need. Aegis of legion makes you more tanky and is good for team. You could get rabadon for more damage. Or you could get some more health or something.
Runes: Seal armor, Mark magic penetration, Glyph flat mana. Quintessence flat health.
Masteries: 21 deffense and either 9 utility or 9 offense.
Have fun climbing the ladders!
Edit: I forgot! I usually dont get wards, but it's nice to buy 1- 2 wards early so you can run back when you get ganked.