Hi, my names Joelacanth (Joel), and I've been playing League for about a year now. I typically avoid Ranked games, so if you're asking for ELO credentials or if I'm Plat V or Bronze V, I cant give you that. What I can give you is a pretty experienced player's guide to one of the most OP champs on the market right now. Cross your fingers and knock on wood that Riot doesn't nerf her anytime soon.

Dont downvote my guide just because I'm lacking credentials. Read into it, read my summaries and explanations, and explain why you think its wrong or needs some fine tuning; THEN downvote it. I'm very big on building a positive community both here on MobaFire which I've used extensively, and within League of Legends. Provide constructive criticism not only to my guide, but to struggling players.

Thanks, and have fun.

PROS:
+Insane DPS
+Capable of burstdown
+Wonderful chases
+ROCKET LAUNCHER
+MACHINE GUN
+Snare and slow utility
+Global ult!
+Incredible split pusher and turret diver

CONS
+Limited escapes (Flash, Flame Chompers, GET EXCITED! proc)
+Squishy
+High priority target

OFFENSE: 21
It's the Standard ADC Offensive Tree, with one exception. Instead of taking a 3rd point in
Havoc, I placed a point into Destruction. A lot of you are probably wondering why. Havoc only adds a negligable .77% of extra damage with a third point, whereas with Destruction, you deal 5% extra damage to turrets. Jinx deals MASSIVE DPS because of her innate AttSpd bonuses and built with damage items, Jinx RIPS through turrets with ease. Even if enemy champs are hiding beneath them. Tear down their turret before they can turn tail and run, and with GET EXCITED!, start the chase and decimate them.

DEFENSE: 9
Standard ADC defense runes.

UTILITY:0
As with any ADC, Jinx doesn't greatly benefit from the Utility tree. Better left alone.

Barrier: Becoming more and more of a standard choice on ADCs of late, and with good reason. I've been able to secure more kills and make more escapes with Barrier that I wouldn't have made with Ignite. 9/10 times I'll take this over Ignite.

Flash: A must have on Jinx. She has no innate escapes other than Flame Chompers, and unless you time and place those well, they're useless.

Ignite: Secures kills, prevents them from healing and jumping back into the fight, and whittles away at their health. Always a wonderful choice. Personally, though, I prefer Barrier.

Max your Q first. When Jinx first came out, everyone, and I mean EVERYONE, was maxing her W first. And why not? It deals INSANE amounts of poke damage. But think about your role as an ADC. Your primary job early game is to outfarm your opponent, to trade, and to ultimately snag a few kills. ZAP!, while an incredible poke tool, has limited trade capability with a high cooldown and it can be blocked by creeps or supports. I find that the ramped up AttSpd from switching to 'Pow-Pow!' aids immensely in last hitting minions and trading off with enemy champs once you have BF Sword or Double Doran's. This also adds range to your rocket launcher, Fishbones, which, when they escape out of range of Pow-Pow!, you can snag a few more hits to secure a kill. The added range also lets you stay out of THEIR range when you need to play a little passive. I'll explain why I max Q first further in the itemization section. It will all become clear then.

Next, max your W, ZAP! It's a great poke, applies a slow for chases, and reveals hidden enemies. Definitely take one point at level 2 to catch those sneaky guys creeping up through the bush to nab you, or to poke a little to aggresively zone them out.

Next, max Flame Chompers. It's a 'one-point wonder' skill, dealing 120(+100%AP) (DO NOT BUY AP FOR THIS ONE SKILL, IT IS NOT WORTH IT) with one skill point. 120 damage is a fair bit at level 3, considering most champs at level 1 start with around 500 health and don't have a significant amount of growth to their health. Max this last for extended stuns in escaping team fights and a little extra damage.

As with all Ultimates, max SUPER MEGA DEATH ROCKET! At levels 6, 11, and 16. SMDR, (which I like to shorten to 'SMD'), is a long range global ult. It deals 150/200/250 (+50% AD) at short range and depending on how far the rocket traveled, it deals up to 300/400/500 (+100%AD + 25/30/35% of targets missing health). Yes, that's a LOT of damage. Maxed out, with this build full, at full range, thats 670 DAMAGE + 35% OF THEIR MISSING HEALTH.

CORE:
Infinity Edge: Standard Item for ADCs

Bloodthirster: Another standard for ADCs

Now let's talk about this weird itemization.

Why not Phantom Dancer? Why Runaan's and Stattik Shiv instead?

Let me explain: Runaan's applies on hit effects. THIS INCLUDES THE EXPLOSIONS FROM FISHBONES. So every time you shoot Fishbones while you have Runaan's, you're shooting not one rocket, but three, and dealing splash damage through entire creep waves. Combine that with Stattik Shiv, and you can wipe out a creep wave in 2 shots. Not to mention that the extra shots from Runaan's also make Stattik Shiv charge faster.

Here's where I'll explain why I max Q first: The faster she shoots, the faster the Shiv charges, significantly adding to her DPS.