[Update: WE'RE BACK!]

Hello! I'm Saigyouji from the BR region, Gold IV at the season reset.
While Kindred is my highest mastery, I've been playing Kennen since Season 4, where he was my main, before becoming a midlane pocket pick since I switched main roles.

However, now that my boi's been in and out of the meta, I thought I'd throw this out there for anyone trying to get out of low elo with a reliable midlane mage who isn't Ahri. (No, Diana isn't a reliable low elo midlane mage either.)
Oh, I won't bother covering skills, backstory and all that jazz, since you should obviously be familiar with the former before taking him to ranked.
Without further ado, let's get to it!

By the way, comments are appreciated!

Well, why not? He's reliable, can be really damn strong if ahead, and is without a doubt League's cutest champion!
(Totally not biased I swear.)

Of course, there are mid laners who can become bigger murder machines than him, but this is low elo, so you'll need anything you can get to give the enemy as much cancer as possible for extra tilt.
And if you ask me, free stuns every few seconds during a team fight is more than enough for that!

All he really needs now is an Ezreal-type update and we'll all be set!
(Riot pls give him some love)

Poke. Poke. Poke. Poke.

No matter your matchup, no matter your skill level, no matter your elo, Kennen will always be primarily a poke-focused champion. If you took the standard runes, you should be making a decent amount of extra gold while at it!

Get used to the timing of that Q as soon as you can, your opponent sure won't. But also don't spam it enough to run outta energy and be caught with your pants down!
One important thing to note about that skill is that the hitbox is a little bit shorter than the animation. Even if the Shuriken keeps going, there are times where it won't actually connect with the enemy.
It's a pretty annoying bug that's been there since release and hasn't been fixed.

Use your W as often as possible if you hit the enemy with any of your skills. It's literally just free damage so why wouldn't you.
The passive part just helps with farming, securing stuns, or doing a little extra poke damage. Line it up with the rest of your combo and you got yourself a guaranteed stun with only two skills!

When you've worn them down, both with your skills and basic attacks alike, you can just go and finish them off with no problem. Free stuns and ignite should be all you need! Seriously, the AP scaling is higher than anyone expects for this cute little bugger.

Remember though, due to changes to his E, you won't have a get out of jail card anymore with the extra Armor/MR. Save it for when you really need it, either for an all-in you're 200% sure you'll win, or for getting away from ganks.

Unless you're against counters or losing lane, you should also be pushing lane priority so you can give that salty duo in your bot lane a bit of a hand.
(And maybe secure dragon while you're down there!)

Ready to be the second jungler? No? Too bad.
Better practice that game vision and ward placement!

Take that first midlane tower and immediately start helping the other lanes.
Give your ADC some kills so they won't be worthless, stop that 4/0 Riven stomping your onetrick Jax on top for some easy shutdown gold (but don't take any unecessary risks while ganking), help with Herald/Dragon as often as you can, grab scuttles, etc.

Your job here is making sure your lane isn't the only one winning. Remember, no matter how good you are, your team has a 70% chance of being horrible at finishing games, so you'll need that advantage for everyone.
If your enemy starts following your example and ganking a lot, simply follow and countergank. Should get a few kills out of it if your ult's up!

Once grouping phase starts, it's pretty simple. You are a teamfight champion, after all.
Make use of that ult, W and Zhonya's to give the enemy team's backline a headache.
Delete that tryhard Vayne in the enemy team before she can even ult, and then just focus whoever is the second strongest in the enemy team (unless they have a healer).
Push for objectives and towers as often as possible, of course. Yes, even if it means giving up some sweet kills.

Now here's where things get tricky. You can't just jump in and ult as often as before. If your team is ahead though, it should just be a matter of picking off their jungler, forcing baron (or baron baiting), and heading straight to their base.

Hoooowever, if you're behind, your best bet is making use of the enemy's overconfidence. Unfortunately, you'll have to rely on your team to help you with that.
If they're not too busy raging, flaming, and getting themselves killed, it should be pretty easy to get some help and get rid of the enemy ADC while they're spamming mastery and shooting your tower.

As soon as 2 or more people are dead in the enemy team, and you know they're not about to delete your entire base, go for that Baron.
You know what to do from there.

A simple and rough guide that will only last you until you're out of Low Elo.
However, I hope that it will still be helpful to any other struggling climbers!
Anyway, have fun and good luck!