Well this is how i jungle yi both in ranked and normal i will explain my route item order and finishing the build if the game lasts long enough which most of the time it wont

marks arm pen = late game damage
seals armor = i used to use dodge seals but 7% dodge just didn't feel it was good enough so switched them to armor for late game survivability
glyphs att spd = your yi why not lol

first you get your madreds then boots then wriggles and beserkers greaves after that the crit from a ghostblade then finish and go on a massive ganking spree lol and make ur way through the build when finish upgrade ur lifesteal to either a starks if no one on ur team has one or a bloodthirster and ur greaves to a phantomdancer

i start with cloth armor and 2 health pots start at twin golems alpha strikke smite the 1 that get proced then onto wraiths then wolfs then back to base to buy a longsword most of the time still having 1 health pot then repeat this time finishing madreds when i go back and still having that one health pot then on blue buff after i get blue buff most of the time i help top which is most of the time the solo lane while waiting for smite to come off cd by that time i go back n get my boots and head for red buff and lvl 6 from there is gank push when u get a chance and help denfend towers that get pushed hard

in team fights u should initiate but if u do i alpha strike in and drop to a meditate hoping they dont stun me stop it lol but ur main job is clean up - squishy slayer so for most part u wipe out the highest damaging enemy n work ur way down the list

constructional criticism welcome please comment n let me no what u think