Hey guys :) I am from Germany so excuse some spelling/grammar mistakes please :/
I have played Nami to M5 now (don't have enough blue essences to upgrade to M6) and I simply want to share my usual Nami Support tactics with this guide :3

Please Notice this guide isn't finished, yet :)

Champion Spotlight

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+ UTILITY + huge teamfight potential + good CC + sustain

- hard to master (especially bubbles) - useless alone, needs team - mana problems - squishy

Cunning

I choose Wanderer for more roaming potential and Secret Stash for more sustain and because the other options are pretty useless.
Then, I pick Meditation to solve my mana problems (they arent solved, but better than nothing ^^).
Bandit for extra money (think thats clear) and Intelligence for some extra CDR.
Then you can choose between Windspeaker's Blessing (defensive) and Thunderlord's Decree (VERY offensive). I recommend Windspeaker's Blessing , you are not Sona!

Resolve

I like to pick Perseverance and Recovery for even more sustain, so I can heal my AD Carry, to deny mana problems. Further more I pick Runic Armor to boost heals on myself ( Ebb and Flow or even Heal by AD Carry.
Tough Skin should help you while trading, but you can also choose Explorer for quick mid ganks :)

This are the standard runes, I use for mage support. They grant you some poke potential and Armor + Magic Resist. Very important for me are the 4 Greater Glyph of Mana Regeneration.

Of course you can use a even more powerful poke variation; maybe this one: