Dont pick Master Yi as jungler if your team has not 2 tanks and has strong CC skills (top and supporter should be tanky).
Don't pick if you dont know how to play jungler. O3O
I don't want and can't teach how to play jungle. Play and learn yourslef.
If you have teamfight, participates teamfight after 3 sec later.
Master Yi is strong to who left half HP.
Dont fight without Highlander.
Buy wards every time.

Smite is required spell of junglers.
Teleport offers quick backup. That helps Master Yi participate teamfight quickly while destory turrets.

Highlander > Alpha Strike > Wuju Style > Meditate

Alpha Strike If Master Yi has not Alpha Strike, Master Yi can't be jungler. Alpha Strike has 50% chance to deals 260 ~ 500 bouns magic damage to monsters. Dont use Alpha Strike for first attack while gank. Use Alpha Strike when enemy run away with Flash.

Meditate restores HP. It restores 400% AP, but this build for AD Master Yi.

Wuju Style increases 15~35 AD. If activated Wuju Style, it increases 30~70 AD. This makes to have high AD than other AD carries.

Highlander is Master Yi. It increases 40~80% attack speed. And if kill enemy, refreshes all of Master Yi's cool down. If Master Yi kils enemy while activated Wuju Style and Highlander, Master Yi gets 105 AD (if Wuju Style is 5 lvl).

Berserker's Greaves increases 20% AS. My build doesn't use Phantom Dancer, Sword of the Divine, or Zephyr becuase Berserker's Greaves, Greater Mark of Attack Speed, Fury guarantee 40% AS and Highlander guarantee 40/60/80% AS.

Enchantment: Distortion is good for Teleport. Enchantment: Distortion and Mastermind decrease 35% cool down. It becomes round 200 sec.

Wriggle's Lantern gives one ward every 3 min. We can use for backdoor with Teleport and destory turrets, To destory turrets, you must know where are enemies and always ready to escape. Wriggle's Lantern deals bonus damage with 25% chance. If makes to hunt dragon alone. Wriggle's Lantern is good because Master Yi basic attack to hunt monsters. Wriggle's Lantern helps to quick clean your jungle camps.

Bilgewater Cutlass helps to gank. Bilgewater Cutlass makes slow enemy movement speed. Master Yi is hard to gank without Red Buff because he does not have CC, but Bilgewater Cutlass give a CC Ability.

Blade of the Ruined King is Bilgewater Cutlass's next item. These day many champs have Warmog's Armor, so Blade of the Ruined King deals more damage and heals more HP.

Warmog's Armor is OP.

Last Whisper reduce 35% enemy armor. It helps to increase Blade of the Ruined King's bonus damage.

Bloodthirster guarantees 70~100 AD and 12~18% life steal.

Black Cleaver is another OP.

My build gives up AS items like Phantom Dancer, Sword of the Divine, or Zephyr, and I use Warmog's Armor as defence item instead of AS items. And Master Yi is not range carry, he is melee carry. Most carry champs deal damage with basic attack. So I give him 2 or more life steal items and one defence item to cover weakness of melee champs.

start jungle
wovlf > bule > wraith > red > golem

While you'r jungling, your team need help or is attacked by gank or Roaming:
if you can help them(you are near by there), go to help them even you'r hunting.
if you cannot help them(your far away from there), go to counter jungle to disturb enemy jungler's growth. But teleport is existed my build. lol

start jungle
wovlf > bule > wraith > red > golem

lane is pulled, go gank
lane is pushed, don't gank
before gank, always check enemy's HP and Ping on enemy to teammates respond your gank.

Just push lane and destory enemy turrets.
If teamfight start, use Teleport and quick backup team.
Alawsy ready to run away while push lane and destory turrets (your supporter shuold know how to play supporter). Many low lvl supporters dont buy sight ward even 30 lvl.

P.S. if you play supporter, buy enough wards first then buy your items.

If you have teamfight, participates teamfight after 3 sec later. That means, attack enemy after they used C.C.
Personally I think, attack offtank first with your AD carry beacuse most offtank has Warmog's Armor, but we have Blade of the Ruined King.

P.S. Buy wards even you are not supporter.