If you want to play Shaco you have to know him. I´ll show you how to play him.
I hope you will enjoy my guide!

You should start with Boots of Speedand 2 Health Potionsand 1 Mana Potionfor laning to level 6. At next you have to build your Boots of Speeds to Sorcerer´s Shoes. Then i think Rylai´s Crystal Scepteris the best because Shaco is sqishy and 500 health aren´t bad for him.
Then Rabadon´s Deathcappushes your Ability Power, with 140 Ability Power and 30 % increased Ability Power is this item a good choice for Shaco. Then build Archangel´s Staffand a Rod of Agesfor more Mana and Ability Power. IMPORTANT: When you have equivalent or more Deaths then Kills, don´t buy Mejai´s Soulstealer! When you have this, buy Lich Bane.

For Shaco i use Flashand Igniteor Ghostand Exhaust. You can also use Teleport.

For farming your E the Two-Shiv Poisoncan help you a lot. When you´re at laning phase and don´t want play agressive then wait until your target (a minion) has low live. Now use your Two-Shiv Poisonto get the Gold without going melee attcking. Sure, you can´t do this all the time (no Mana, Cooldown) but your E skillcan be very good for Farming Minions.

At the Laning Phase try to get in the bush until the minions didn´t spawned put all the time Jack in the Boxesin the bush. When the Minions are fighting, come out of the bush and place your Boxesin bushes, on the way, and in minions fights. Don´t forget! Your Boxes fears the Enemys when they come in near of them. Try to throw your E skillon the Enemy Champion when he is going to be agressive.

Your Q Skill Deceiveis good at team work. Bevore a team fight make sure you have much Jack in the Boxesin the Jungle, that they can´t flee. You have to fokus the sqiushy Champions like Ashe, Veigar and so on. Jump behind them, place a Jack in the Box and throw your kniveon him when you can´t kill him with this combo activate your Ulti and it´s done. When you´ve pushed the Enemys to a tower and they´re damaged, activate your Ultiand send your copy to the hurted Enemy.

Pros:

The E Skill

slows the enemy
Shaco can do a combo that can kill Enemys fast
The Enemys can get nerved from the Jack in the boxes When an Enemy try to run away do your Deceiveand it´s done
Your Boxes can kill Enemys when you´re deadYou can flee with your deceive When you have low life and the enemy too you can send your copyand he is dead

Cons:

When you don´t buy an Health item at the early game you CAN feed.
When your enemys have all high life you can´t do much
Shaco can be pinged by the enemy, so they can differentiate between you and the Copy

Thanks for reading my Shaco AP guide!
I hope you enjoyed it! Let here a commentary :)