Well, i like Lulu... but look... in the championship who choosed lulu support, they lost a game... what do you think? In my opinion she's weakest support now

Lulu Support is my favorite, but I am still learning so take anything I say with a grain of salt!

I try to save my E for shielding. Generally I will only throw it on an opponent if I am trying to increase the range of my Q by shooting from Pix into a bigger group of the enemy. Tricky, but fun when it works! Otherwise I find the benefit of the Shield on an ally (or myself) is a better use of the mana. Are you able to keep your mana regen up enough to keep harassing with E? If so, there shouldn't be a problem, it just doesn't work so well for me, could be my relative lack of experience.

For poke/harass I stick to my Q, I love that it has a slow effect, plus range can be changed/increased when you have Pix on an ally or opponent so it can tag them when they don't expect it. Auto attack is also a great tool, since it has some range on Lulu and can save you some mana in the early game.

If I feel like someone is getting too aggressive on my carry I love to throw a W polymorph on them - kind of a way to say "You want to play with us... try playing as a Kitty!" (Squirrel or Cupcake, if you're not using the Wicked skin, but I always play Wicked Lulu for now.) I do need a little practice using Whimsy as a get away tool, for me and my carry - I just love to use it for crowd control SO MUCH! It's fabulous if you can follow it up with a Glitterlance to slow them, too. In that case they are set up really nicely for some serious damage.

As you can tell, I think she's a totally viable support in ranked games, especially if paired with the right carry.

I have been support lulu since day 1 and i do play a lot of support though I am not a high elo player - I too harass a lot with Lulu's E but it is situational - if you're having success bullying, continue doing so - but if it's a lane with a lot of sustain ie soraka/sona - you may find that you aren't getting anywhere with it. In this case, save E as a shield. Once again, it's dynamic so there's no hard rule. Support lulu is viable though it probably isn't as strong as supports such as Sona or Alistar.

Hello! Support main here.

My thoughts on Lulu are that she is a great counterpick to hyper carry AD characters (Vayne, Tristana, etc.) She provides so much late game disruption, poly, exhaust, ult, slow, that she can take the carry out of the game in team fights. In addition, she has strong lane harass with her auto attacks and E. Unlike Copper kitten I almost never harass with my Q. I save Q for a chasing/ disengage tool to help secure kills. Almost all of my harass is from my E and auto attacks.
I feel that she is best played as an extremely agressive support. She can zone the entire lane herself until around level 9 and give your carry free farm.