Bypass the ability power, damage to minions, magic pen., and rally masteries in offense, and put 22 (or however many you have to use) into the rest of them... defensive masteries aren't all that important because this build is an offensive build as Master Yi is an offensive champion... put the rest into utility where ever you see fit just so long as you put 4 into the one which causes you to gain more experience... if you can level faster than your opponent it will just make raping them that much easier.

For the most part you shouldn't have any problems with this build at all, but if you see where something doesn't fit (for you) feel free to swap something out and tell me about it so i can check it out and see if i like your suggestion better than my own lol... the order of the purchases isn't all that important this is just the order in which i go... the mallet is just to slow them down while you are pounding on them so they have a harder time escaping... to appease people that misunderstood the purchase of atmas impaler (it wasnt for the passive) i have replaced it with an infinity's edge

Marks: these should be crit damage since you are building a build that will cause you to be "criting" often
Seals: go with attack speed because honestly who couldnt use added attack speed lol
Glyphs: i elect to do the same here as with marks, but that is just me you may find a better choice for your style of play
Quints: health health health enough said

this is just the order i level up my abilities... i find meditate to be a waste of time unless you are going with an AP build which i have found to be a fail choice with Yi