1 - Introduction
2 - Laning Phase
3 - Items
4 - Team Work
5 - Late Game

Master Yi on top side is more of a fun pick than a serious carry pick but he has a lot to offer.

Master Yi has the advantage over non weak early levels champions (such as Jax, Jayce) and against champions who have no Cc. [Q] Alpha Strike will give you a very big tool to use during the first levels (farming safely and pocking).
At level 6, [R] Highlander will just make it easier for you (if you're ahead and feeling confident over your opponent, try some all ins and see how strong you are and if how he reacts to it).

The core items I'm giving you can be iriented on way more tanky one if you're not ahead or if you're getting beaten, I suggest to go BOTRK, Dead Man's Plate, Titanic Hydra, Banshee (depending on your matchup) and Mercury or Ninja Tabi (depending of your enemies team composition).

If you're ahead but your opponents have some Cc to deal with you, you better have to go in team fights after they used their major Ccs, don't forget, it is a team play game, even when you're playing with Master Yi ;)

If you're in the tanky build, you can engage by yourself if you're followed by your team, you will be the frontline and you can work with [W] Meditate to stay in the fight and take damages as long as possible.

This is time for you to be the real Highlander, late game Master Yi is at his best potential, you can run on your opponents like crazy, push like nobody will stop you, and fight till you die!