Try to get Sabre as fast as you can, you can take the Blade too, if you want to slow enemies, if you dont have much cc in team.

Do the jungle how fast as you can, to get the devourer, and stack it.
You should have your devourer stacked before 20.

Try then to gank enemies, with your E>W>Q, to slow then, and knock them up and make your cooldowns lower.

When you got your guinsoo rageblade, and devourer, you can now easily kill every champion.
You can jump in, and keep healing from enemies cause of your W.

You can splitpush, you are healing when attacking tower.

In Team Fights, try to pick op the adc or apc, you can easy slow him down with your E, and deal a lot of damage, and make your teammates easier kill the slowed guy.

You can knock enemies away with your R when they try to engage.

You must take the smite to jungle, to have smite buffs, and to have better clear.

You must take the flash, to be able, to run away from enemies, juke.

Pros:
You got a lot of sustain from your W.
You can easily tank towers, cause you are healing from them.
You can easily pick up someone with your E.
Strong mid, and late game.
A lot of mixed damage, against tanks, cause its hard to build armor and magic resistance.
Easy ganks

Cons:
Can be easily bursted by enemies
You have no escape
You must stay in jungle
You can get counter jungled
When you die in early game, you are weak in mid and late game
No hard CC