I use AD Seals,AP Glyphs,AD+Magic Pen Marks and AD/lvl Quints, For early games dominance, much DMG at low lvls to sustain lane.

I Max out mark of the assassin as soon as possible, for the dmg buff and good nuke dmg
The I max out the ulti, Shadow dance for easy and good chasing, Good to initiate
Crescent slash is important, its good to farm minions, cuz its the only 1 aoe but its good to kill champs too
Twilight Shroud i keep low till end game cuz its good to run or kill in but asa u do it ur in it a little but u gonna get out fast so the tiem doesnt really matters with this build

Pros:
good damage early game and late game
good for initiating
1v1 instant win
tank shredder
turret shredder
Cons:
You get focused alot
early game squishy
if stunned your done

You should use: Mark Of the assassin, Shadow dance, autoattack,twilight shroud, Mark of the assassin auto attack,crescent slash,mark autoattack, do it over if he/she didnt die yet

I Use this item build, because it gives you early game dominance and lategame big big big burst damage so you can kill someone in 5 seconds or faster easyly so teemo and eve, you're done ;)

Play a bit carefull at start last hit minions with mark of the assassin, facecheck brush with twilight shroud, Poke with mark of the assassin, if u are sure u can get the kill, dont hesitate, just go for it, Use ignite w mastery for first blood easyly ;)

My first build so if it aint good tell me the items and runes and combo works so try it and comment ;)