Hi THERE! My name is Albert Winston (not my real name) . I am also Plat V (actually my real rank).
is a champion that shines exceptionally well early game thanks to her high damaging spells. Her somewhat easy harass spells doom for most adcs and supports who hesitate. In an ideal world a would want to be as aggressive as possible and this is true at all lvls of play. Keep the fancy schmancy double range Q's to a minimum in the "Trade" phase. Primarily use it harrass under their tower for quick cheap dmg and to land a crippling slow on an out of position target. Towards middle to late game goes through her ugly duckling phase and instead becomes a CC powerhouse. Forget doing mass damages.(everyones going to have a cinderhulk anyway) Your job is to now to use your shield to mitigate damage and using whimsey exclusively for poly-ing threatening targets. Your Ult is now used MOSTLY for peel. But if your bruiser boyfriend from the toppest of lanes or the janglest of jangles lands a good initiate to tear up the unsuspecting buttholes of the enemies back line...you should probably toss on them for schweet pentakills.
Because Lulu lacks a heal and more than likely (thanks to ritos swell champion design team) the enemies will have an assload of CC and stuns that last about a billion years its paramount to pick the Ye Ol'
. You would want this regardless of enemy team make up since it will give you sexy mana regen (For super duper spell fuel) and a healthy spunkchunk of CDR (For massive pew pews and Hugifys)
Your goal is to get 35-40% CDR and really learn how to manage all your skills. In Teamfights i traditionally forgo actually using AA's because lets face it all your damage comes from Qs and passive (Which will be going off annnnyyway cuz of pix's adorable little ass) and focus on casting my skills. Because the tank meta (Fuck this game) makes teamfights last like 20-40 years (10-20 secs) you will probably use your skills so many times that playing lulu past 10 games will have your qwer keys dead and broken.
Don't be afraid to use Up we go! (Ultimate) because holding spells is for fucking losers. Especially if its on a 60 sec cd.
So what do you say sport? Lulu is pretty good right?
WELL HOLD ON JUST ONE MINUTE TIGER there are something things you should know about your little fae slut yordle.
She dreads champions with easy ins and brain dead initiate. You guessed it. Playing Lulu isnt such a gollygee idea when the enemy team picks 
or in true dickcheese fashion 
.
Now you might be shaking your little head saying "But gee albert-senpai (Not my real name) why do i even play lulu when Leona and Nautilas are such freelo gods with overloaded kits that make them terror to practically anyone in botlane?"
Well there, champ. Thatsa easy to s'plain! While leona is almost good all of the time and she gets a free 50-70 MR and Armor by just hitting W (Fuckin ridic right?) she can be easily bullied in lane and starved.
Now listen here ya little shit. This is where the real good lulus get seperated from the korean ones. A good lulu knows how to safely harass outside of Leona E range and can effectively dodge most of her skills. And if you really want to be fancy and leona jumps in on your adc all you need to do is to throw all your spells on the enemy adc (And by all your spells i really just mean Q and W. E your adc) and in most cases you should be fine. Nautilas however is a different ball game, sonny.
TLDR; just don't pick lulu against Leona and Naut. Or if you do make sure you don't go ap runes and just start out tanky.
"Ne-ne! Albert-sunbae! Whats your favorite lulu skill?"
Whimsy of course! Not only does it give you a nice 30%+ movespeed. But even better Its a FUCKING EXHAUST! Thats right, jimmy! TWO EXHAUSTS. YOU HAVE TWO OF THEM. The most important thing to do is lane skirmishes is to CHAIN THEM. don't throw them both on the adc at once. tahts retarded. More then likely you'd want to W them first. Then as that ends you exhaust deeem! Rivens? NO! Jax's No! Hecarims? No! Whimsy a bruisers, assassins, adcs, worst nightmare.
Whelp! Ive type this wall of text and now i reread the OP's question and figured out he didn't as for a how to lulu guide! Fuck my life! But i want everyone to come across this and read it anyway.
Also never upgrade 
. its fucking garbage. Infact it would be better to sell it when you have excess gold and buy Yellow support item flat out. If you already have Cruicible this might put you over CDR cap which is bad. idk.
ALSO REMEBER THIS. 10% CDR costs 600 GOLD! 600! If you have 10 CDR from runes and masteries 600g gets you 20%. Thats crazy bonkers.
All praise 
, see how that goes.