Ok at first i have to say that i will make a really short guide, everyone who thinks "oh no ad lulu is so bad" please try this build more than once and comment this guide after that.

This Guide contains:
1. Items
2. Skills
3. Farming/Playing
4. Summary

Ok here is the important question: "Why shall i play AD Lulu ?!"
In fact Lulu's passiv Skill is so great. With every hit you do, Pix will shoot 3 bonus hits with total 15 magical damage on level 1 and 115 magical damage on level 18!
That is pretty cool because the enemy may buy armor to fight you, but ur passiv will make still a lot of damage.
Thats also the reason why the ad guide is build of attack speed! Just to do so much output with your passiv skill.

Ok Items - Let's go!

At first i have to say that u should play Lulu not at the botlane. It's possible but in my experience it's not so effectiv like solo top.

So for solo top it's important to stay a long time on your lane, this is why i go for life regeneration first.
Philosopher's Stone is in my opinion very important for the early game, because you can spamm you Q and you will gain some extra gold.
So after that the real Item build begins:
Attack speed is for the first so important to win against the enemy, so go for Berserkers Greaves and Wits End. The passiv effect of Wits End in combination with your passiv Skill is a real great. So the most of you will think that you do so low damage and that true - but you do a lot of "small" damange in a short time. Well but actually this is quiet not enough. So go for Bloodthirster and Frozen Mallet.
I think i don't have to tell you why you should use the Bloodthirster. Frozen Mallet is so important because enemys can't escape so easy and you will give them a lot of hits when they try to run away from you. If they fight you, you will be glad to have the bonus Health from the Frozen Mallet too.
Ok the build is quiet fine, but not complete. With a Phantomdancer you will be very fast in farming and moving. This movementspeed is great to change lanes quick and defend tower / backdoor. So the last Item: Shurelya's Reverie is for some support and fast pushes. If you dont want this, you can buy another bloodthirster instead.

Passiv: Pix, Ferry Companion
So this passiv is awesome, Pix will shoot 3 times with every of your auto attacks.

Q: Glitterlance
This skill will reduce enemys movement speed and is great to chase enemys or for just doing some damage on the lane. It's also nice to farm minions but keep in mind that a hard pushed lane is dangerous. If you combinate it with your E it will have an awesome range too.

W: Whimsy
Ok now here comes the skills with an effect on allies and enemys. In fact you are AD and so i will just explain the effect on enemys.
This funny skill will transformate the enemy is a cute pet which cannot attack or use any skills. When you fight against Katarina or someone like that, you can stop her ultimate with putting W on her, thats quiet effectiv and brings the enemy on rage :)

E: Help, Pix!
So when you put E on an enemy Pix will go to him and dealing some damage, you can also see where the enemy goes. An effectiv combination is to put your E on a minion and than using Q, because Pix will fire one Glitterlance too. So you have an awesome range to slow the enemy. Good for chasing ;)

R: Wild Growth
At first I have to say that I love this ultimate. It will give you or an allie some extra health and when using all enemys will pushed into the sky and slowed. So use it for the begin of a teamfight on your tank, or to supprise the enemy when he thinks he can kill you, so you put out your ulti and instead of get killed you will kill him :)

It's oh so easy:
Just right click a lot!
Click on an enmey when he is in range and if not you can farm minions easy with Lulu.
Its quiet effectiv to play solo top. Don't push the lane, let the enemy push. On Level 6 your jungler should come for an gank. When he stands next to the enemy put your R on him and you can kill him easily, if your out of range, may you could slow him with doing E on your jungler and Q in the direction of the enemy. May this range will slow him to get in auto attack range.

In teamfights its so important to set the right focus. Dont think that Lulu is a tank, stand in the second row and attack the enemy's damage dealers when they are close enough. If not: stay out of range of them. You can hit the enemys Tank in this case, but keep your eyes open when you should change focus. A lot of people are very scared when you show them in the early game that you will not play as a support. So try to hit with Lulu as much as you can, but keep focus by the minions. I alway try to stay on my lane until i got 1800 Gold, so i can buy alot of staff. Lulu's health regeneration is quiet low, so you should mind to buy some health potions when you are in town.

Also the enemy will not believe that you play Lulu as AD because most of them never saw one.
That's your chance to show them that it's working ;)!

Pro's
-The W Skill is very nice for an AD carry
-The R is nice to survive, to help and to engage enemys
-With full item build is Lulu the perfect Hunter
-You dont play only Lulu - dont forget that you got also Pix!
-great combinations possible (for example: yous R on a friendly Katarina when she is in her ultimate. This won't allow the enemy to escape out of her ulti so easily)
-dealing damage very fast
-AP Lulu's Skills are not so easy to set, and they got cooldown - Pix dont

Con's
-in early game Lulu is very squishy
-low movement speed / except you are using your W
-easy to gank when you push the lane to hard
-Not the highest damage

I'm sorry guys, but i don't know how to fill the remaining letters. So i just can repeat that Lulu is relly great. Riot didn't lie, she is a new way of support... support by killing enemys.