Leesin, the Blind Monk is one of the strongest jungler with his sustain and his damage output on Early Game. Leesin's Counter Jungling is one of the easiest, allowing him to Counter & run by using his Safeguard. However, Leesin is one of the hardest Jungler to learn & master.

[Pros]

Insane Mobility.
Great sustain in Early/Late Game.
Awesome Ganks, better with Ult available.
Unexpectable damage output.
Gap-closer with Safeguard.
Awesome Passive w/ Attack speed & Energy Gain.

[Cons]

Hard to master.
Difficulties escaping from opponent early game.
Weak Crowd Control.
Hard to catch-up in Game if you're behind.
Must build tanky to be useful in Late Games.

As usual, Smite & Flash are used for most Junglers. However, it is crucial for Leesin. You need it to make a lot of ridiculous plays & most probably (Ward) > (W *Safeguard*) to get nearer to your teammates, or your opponents.

Start with Blue. (Smiteless)
(Q, attack 2 times, Q)

*RISK* Rush to your Enemy's Red. (Stay in bush & wait for them to hit Red low, SMITE)
If you're near to your opponent (E, attack attack, E, attack attack, Q, dead.)

If not,
starting travelling to your Red.
(Q, attack attack, Q, attack attack, E attack attack, E, SMITE.)

If there isn't any lanes to Gank, continue to farm more at your Jungle.

More are going to be post up soon.