Hello everyone! This is a guide that will help you jungle with Master Yi, The Wuju Bladesman.

You have to pick runes based on where do you want to be strong. If you want to be strong on early game and get the easiest jungle as possible, get attack damage runes, and if you want to be strong on late game, get armor penetration runes.
I take armor penetration runes so I can kill the other team's carries, even if they are doing defense against me. The attack speed runes help you triggering your passive more times while you are still in the jungling fase, making it easier for you to kill buffs.

For Summoner Spells, I like Flash and Smite. Smite is needed if you are jungling and Flash is very useful to escape from enemies when your ult is on cooldown, but other Summoner Spells like Exhaust and Ignite can be used, especially at early game.

Start with Cloth armor and 5 potions and head directly to the blue buff.
Watch out for enemies ganks there, because that is where most junglers start.
Just start attacking the golem with Alpha Strike and when he reaches 445 health, end him with Smite.
Clear all the normal monsters once and you should have Smite again. When you do, go to the red buff and do the same as you did with the blue buff, and start ganking.
When you see someone on low health, go to their lanes, hide yourself and when get to your Alpha Strike range, jump on them and use your buff to kill them, getting some gold.
Keep jungling until you see someone on low health to gank.
When you get 920 gold, get Beserker's Greaves, keep jungling and trying to gank.
After you get the Wriggle's Lantern item, you should have no more problems in jungling. If you aren't level 6 yet, go farm some more jungle minions until you get you ultimate.
Jungling now should be used only to get buffs, and your priority now is to get good ganks.

On late game, your priority is to kill carries that are protected by tanks, like Caitlyn and Annie.
To kill those champions, all you need is to wait, hidden, until the fight starts, and when it happens, you get behind the enemy team and kill everyone, starting by those carries.

Well, this was my guide, I hope you liked it.