I usually always like to only farm in the laning phase. In good matchups you can also trade by auto attacking and tumbling right after for an auto reset. If the enemies have poke champions buy a doran's shield and try to get all the free farm possible. You can try to freeze the wave and wait for the jungler to gank or if you have enough hp and they dont have a minion advantage your support can engage and kill them. Even if you dont do anything in the laning phase and stay even on farm you will still most of the time stand on top when you get ie and shiv.

Buy this after a bf sword to help you wave clear and create huge burst.

This is the second core item for vayne, rush it after shiv. I'ts passive makes you'r critical hits do so much damage

Great item to get more critical hits and attack speed. It also helps you stay alive in team fights.

This is the alternative item for phantom dancer. Most of the time phantom dancer is better than it, but if the enemies have no assassins it also works

Amazing item for kiting and killing tanks. I almost always buy it as the 5th item. If they have no tanks you can buy bt or against heavy ap maw of malmortius

Great against full ad comps for the armor and just keeping you alive. Buy it for the last item and sell it when its on cooldown.

Good item to counter burst mages like annie or syndra.

If the enemies have no cc buy this for the last item. Most of the time mercurial scimitar is a better option tho

Great item to counter hard cc comps. Always buy it against champions like Leona, Malzahar and Warwick.

I would only buy this item if they have 3+ tanks or a Rammus or Sejuani. Since Vayne's w does true damage to tanks you dont really need this item to kill them

For boots you almost always want to go berserker's greaves for the attack speed. If they have a lot of ad you can go ninja tabis as well

Condemn flash:
First channel your condemn and then flash so the target gets stunned. This is great for outplays. Play Video
Q auto cancel:
Auto attack and right after q and auto again. This is great for chacing and kiting Play Video