This build focuses early on life steal and attack speed which allows you to deal damage (attack speed) but at the same time stay in the lane for extended periods of time (lifesteal). Late game this build turns from damage to health and damage with the introduction of warmogs armor and atmas impailer.

The Runes for this build focus on cooldown reduction, critical chance, and mana regen. The cooldown reduction helps with the long cooldown especially early game of alpha strike. the critical chance helps with the passive of the ifinity edge and also dealing high damage fast with the overall attack speed you build. The mana regen helps combats the high possibility that you will run out of mana with the amount of time you spend time in your lane without going back since you have a high rate of lifesteal.

The items in this build focus early on attack speed and lifesteal. This allows you to stay extended amount of time in the lane early game which allows you to farm minions and collect money. Mid game the items focus heavily on damage with the introduction of the bloodthirster and infinity edge. Late game the items focus on health, health rege, armor, and more damage with warmogs armor and atma's impailer

This skill sequence allows you to deal as much damage as early in the game but still self heal with meditation a little when needed, since this build does focus on lifesteal you really dont need the self heal and it really only sucks mana away from better moves like alpha strike and highlander.

Try to lane with someone with a champion who can stun, root, taunt, or surpress the enemy allowing you to get kills very easily with your high damage output and chasing speed adn your ally keeping your target from escaping before the killing blow comes. early game use your alpha strike to harass the enemy champions when the number of minions nearby is low, always try to start alpha strike on a minion away from the champion you want to hit, you might not hit them every time but you'll take a lot less damage this way. However if you're chasing use alpha strike on your target since when you end you will be right next to them to keep pounding away

Definetly get exhaust which allows you to slow an enemy to allow you get more hits before they get to a turrent increasing the likelyhood of a kill coming your way. The next skill is up to you either ignite or clarity are my choices since extra damage is always good, and extra mana is definetly good especially with how fast you'll be going through your mana. Never get ghost cause honestly with your ultimate you dont need it at all, and with your movement speed and ultimate you also dont really need flash but i've seen plenty of Yi's use it I personally dont use it though.