This is my first guide so i will be glad if you leave comments and vote so i fix my mistakes.

Ok here is one trick for more gold:
Go to the 4 neutral minions ( the ones that lifesteal and always are near towers Lighting Rush them and then Electrical Surge and here is it boom = 90-100g for less than 2 sec. Do it in the 2 waves (the ones on the left side and the ones on the right side) then if you want do the same with the wolves. Remember you must have boots for magic penetration, blasting wand and Amplifying Tome to do this with 2 spells. The trick here is to do it without wasting any time and doing more xp. So when your opponent is on a lane you just go near him and kill the wave for 2 sec, winning 100g and some xp, get back on the MID lane (this can only be done in mid lane) last hit some minions do the combo that I explained for early game and go to the other wave (while being sure that the wave minions are not near your tower with a champion who can push the tower or leave it on low health) always make sure the lane is protected for 3-4 sec so you win more gold and xp. Do the same with the wolves a little bit late in the game when the fight is in the mid or when you pushed their tower on the mid so you are near the wolves camp. There is a second thing, you might help your teammates this way, because the enemy in mid lane may say SS in his team chat so the enemies top and bot lane go back, letting your teammates last hit some minions and farm more gold. This way also the enemy bot or/and top lane may loose some xp if they go near the tower. You can choose the right moment to go farm the 4 lifestealer minions camp while some of your enemies is on very low hp (bot or top lane) forcing him to go back or to recall.

Summoner spells i usually get:
* Exaust - good early in the game if an enemy is doing aggresive you can't also get fb with this one.
* Heal - because i don't start with some doran's item (i think it is waste of money) this is the most needed spell and also can't do a bad trick on an enemy for the first blood or just to pick up a bad kill with this spell. It makes a really bad tricks.
* Flash - if there are a lot of mages on your team pick up a flash, kennen is a low health champ even for mages so if there are a lot or ranged champs you'll easily be targeted and this one helps you get out and also you can pick up a kill if the target is running away
* Ignite - if you feel like getting it then do it but i still recommend exaust because early in the game you have no slow.
* Clairvoyance - if you are mid and you feel like you gonna get ganked all the game then get it, it saved my life a lot of times.
* Remember: always get heal and if you don't get exaust then remove the masterie that improves exaust and get the one for critical - deadliness, also if you gonna get ignite get the masterie for ignite.

I go Offensive masteries because it gives me good dmg early in the game and also the last talent is the best from all other masteries.
Utility - there are too much mana talents and you also don't need so much movement speed because of Lighting rush.
Defense - they are good but because kennen is not tank it will be a waste of points and also Offense gives more things needed.

Last hitting minions is very important for getting your passive from Electrical Surge and for gold farming. Last hit minions with Auto attack or Thundering Shuriken, or with Lighting Rush and Electrical Surge for extra full wave minion farm (but wastes very much energy and cooldowns so be sure there are no near enemies).

* Early game: choose lane (if no one is good for mid you should go but because Thundering Shuriken is not a targeting spell and your opponent will stay behind ranged minions if he is clever, get the passive of electrical surge, then hit him with Lighting rush, then hit him once with auto-attack, and then hit him with Electrical surge - good combo early in the game when your enemy still gets behind minions and also stuns which makes it even better)
* Mid game: Ganks - important for feeding yourself try to make all possibe ganks that can be done and steal the targeted enemy with Thundering Shuriken.
Team fights - if you have rylai scepter don't be afrait to lighting rush in the team fight but always be careful, you might be targeted because of your low health
if you don't have rylai then try staying behind your allies and escape if targeted with lighting rush. the most important for now is to go jungle as much as you can (5% chance to get detected and a good way to farm gold faster for rylai)
* Combos: Non-ult - Lighting rush, Thundering shuriken, electrical surge, some auto attacks, Thundering shuriken and electrical surge again. Don't jump on tanks 1v1 without rylai and ult and also you should always be sure where the other 4 enemys are!
Ult combo- Lighting rush, Slicing Maelstorm, electrical surge, Thundering shuriken, some auto-attacks thundering shuriken and electrical surge again.

Amplifying Tome - Great Starting item combined with your runes you start with about
Get Rylai's Crystal Scepter for the super health bonus and the slow effect + after you get Rabadon's Deathcap the ap bonus is about 100.
2x Hextech Gunblade- the ap bonus is good, yeah i know they don't stack but it gives extra spell vamp and lifesteal, also the ad bonus is like a 5th spell for kennen with the passive bonus of Electrical Surge
2x Rabadon's Deathcap - a "must" items for kennen just gives so much ap and more ap = more kills
Sometimes instead of one of the Hextech Gunblades you can get a Zhonya's Hourglass - When a Kartus is on the team (for his ulti), Brand (for his ulti) and a lot more. It saved my life not 10 or 20 times.
Malady - a very good item choice if more than 3 tanks on the enemy team, the speed bonus is awesone for the passive from Electrical Surge it will apply faster and with the Hextech Gunblade it will deal extra damage + adding a mark of the storm wich is just perfekt for your future stun.
You should NEVER get items for mana and mana regen - kennen is energy champ.