Get a sceptar and a potion by waiting for gold. Go to golems and use alpha strike on them. Use smite on the one that didn't take 520 damage. Get meditate and use it. Btw you should have used your potion during the golems. After you use meditate go to the wraiths and use alpha strike. Then on to the wolves. After that if they don't have a jungler go get their golem and wraiths. If they do have a jungle wait to get your golems, wraiths and wolves. After either of those go do your blue and then gank. Or you can go back get boots and then gank.

Pros: Nice damage
Can go ap or ad
great farmer
game changer
good escape ability
Cons: squishy
early game getting ganked is bad
has no stuns or slows

Sceptar gives you 10 damage per hit. When you go back get some boots to gank. Get some kills and then you'll need some damage to hit hard and get some hp back with your bloodthirsters. Infinty edge for damage and phantom dancer so you can crit and attack faster along with movement speed.

I've showed you what to build how to jungle and what the pros and cons of yi are. It might take some time to get used to yi.