Hello, Im very new here. day 1 :D. so this is gonna be very slow and lame but ive played lulu all day and ive done pretty well. with this build. first off shes a support. so you gotta have a decent teammate. if you can get someone with good speed and crits or hard core cc like yours.

So for Runes, its pretty basic. i focus for armor, Mana regeneration, and gold regeneration, and magic resist.
Seals,9 Greater Seal Of Replenishment.
Marks, 9 Greater Mark Of Resilience.
Glyph's, 9 Greater Glyph Of Shielding.
Quintessence, 3 Greater Quintessence Of Avarice.
I feel its best to make her tanky to help with support as well, instead of focusing on AP early and mid game.

Lets start 9/0/21. I have considered going 0/15/15 or 0/9/21. But this is for the early cool down reduction and random AP damage from her q. early game shes really slow and hard to play but late game is where she snow balls as long as your getting your assists mid game. the extra gold is useful for early buys on utility tree, and the fast Clairvoyance is sooo useful early game and for baron/ drag checks.

Alright just try and go with it.
I start with Faerie charm, 3 sigh wards, and 3 health Potions for sustain and watching for early ganks. I also would recommend just trying to survive.
first real buy is the Philosophers stone, and boots of speed if you can. if your doing well in your lane feeding your partner grab the ruby crystal instead. your w can make up for boots for now. next buy should be the heart of gold and boots of speed then. take your pick. after that grab a kage's lucky for more gold per 5. finally start building boots of lucidity. for max cooldown. after you have your 3 gold per 5 items and your boots of lucidity. start build aegis of legion. depending on there team is how i buy the first build. after thats bought i rush a Shurelya's reverie. then i begin my Rylai's Crystal Scepter. is helps with the slows in in team fights. if you have enough get the Giant's belt. if you do not get the blasting wand when you can. after that just focus that Rylai's. after that build your heart of gold into a locket of iron soloria. next sell your kages pick and start a rabadons death cap. Your fully build and made for team fights :D.

I begin her support and get the E, after that I grab her W for poly morp taunt, then her q for slows at a distance. then i just evenly level her W and E. I grab her Ult when i can(derp) and then last i focus her q again.

As a support Clairvoyance is a must in my opinion, and then flash for early ganks escape. heal is nice but you shouldn't need it.
Other options:
Teleport, For getting back to your lane fast.
Heal, just better for sustaing lane and saving an ally or you.

MY summary is I have done amazing. my best game I went 9/6/31. my partner wouldnt focus so i got the kills <.<. ill work on this more later sorry if this was done wrong in advance. I did a brief over your guide. Ill be adding more soon. I know its sloppy. I just dont want to lose what ive worked on so far. >.<