Shaco needs to engage with decieve. After your tank charges in, run behind him and decieve into the enemy's support or squishiest champion. If the aggression draws to you, use your clone to survive long enough to get another deceive. This way you will help your teammates by killing the enemys strongest player.

Start at blue- Set your jack in the boxes behind where the blue giant spawns (not behind the trees). This way you can spam your poison and jack in the boxes in the jungle. Next to the wolves. Spam your poison. On to the 4 wraiths, smite the blue one and proceed to ganking the middle lane. This is about the time you should get first blood. Deceive out of the top bush and attack. Directly after use your poison, you must be quick on this next one. Send your box out behind the target towards the enemy tower. exhaust because your two shiv poison will run out. This will give you some extra CC (jack in the boxes fear). Afterwards you can choose to start ganking more or keep up the jungle then gank.

Madreds- Shaco can gank early as level 3 without boots, he needs to constantly gank to give his team the advantage. But he needs to level, so don't gank so much you get underleveled.
Boots of Swiftness- I like these because in the build you already have attack speed and you need to be able to chase and run in combat. Boots of mobility do not allow you to do this in combat, but it can be very helpful in team fights for escaping.
Wriggles Lantern- Madreds bloodrazor I do not think is needed for shaco, a more critical build to boost his Deceive. The lantern will provide lifesteal and some armor until you sell it for a blood thirster.
Zeal to B.F.- Shaco needs to start building attack speed for his clone and himself, along with damage. This will give you an advantage to not get behind and keep up with other champions.
Phantom Dancer- REQUIRED for shaco, he needs the extra movement speed for ganking along with escaping, it is the perfect item because he needs all of its components.
Infinity Edge- Another REQUIRED item, infinity edge will boost his Deceive, and critical strikes are key to Shaco.
Frozen Mallet- Enemy champions should be starting to get fairly strong by now, and you need a way to survive while still being an attack damage champ. The addition slow will add on the close range and save your two-shiv poison.
The bloodthirster- Lifesteal is important for any ad champ, sell the lantern for the bloodthirster, stack it and you should be legendary.
Black Cleaver OR Banshees Veil- If you are dominating the enemy team, get a cleaver, if the enemy is extremely tanky, get a cleaver, if their nukes are obliterating you, get a banshee. If you feel like you die to easy you should get a banshee.