Heyy! My name is REymart SEnpai and I am the Vayne main.My fav ADC's are Vayne&Draven. In this guide I will try to teach you how to become awesome Vayne player.I like Vayne because of the power she has but also the things you may get with high skill.Ask me any questions below and I will try to respond to them the best i can.
Let's go!

FARMING
Last hitting minions is massively important to gaining an advantage over your lane opponent -- being up by just 30 cs is nearly equivalent gold-wise to being up two kills. This kind of advantage directly translates to your ability to snowball the lane, and ultimately the game.
You should be farming as much as possible, but sometimes it might not be that way. If that's the case, you have to have patience until late game.

You need to wait for minion to kill him in the last moment when he has lowHP16 minions = 1 kill.

TRADING
Ok so Vayne's auto + tumble is definitely weaker than a Draven's auto attack while Q is on or even worse if he has 2 Q on.The best thing for trading in lane is to try your best to trade for 3 auto attacks. This way when you are maxing [W] you will definitely come out ahead as long as you can proc silver bolts.If u have 80%+ mana its not bad to do Q+AutoAttack+E to proc silver bolt. Just remember condemn costs a lot of mana and has a high cooldown so think before trading that way.
Good way to keep on top of your lane is if you have a support that iss not passive (example: Thresh/Alistar/Blitz and not like a janna/sona) then if you see the enemy support out of position, you can use your condemn to knock them against the wall and set up a CC from your support, leading for a possible kill. Constantly look for plays so that your opponent bot lane won't be able to think they can just take advantage of you. You have to show them that you're good!

Night Hunter

Vayne ruthlessly hunts evil-doers. She gains 30 Movement Speed when moving toward nearby enemy champions.

Tumble

Cost: 30 Mana
Range: 300
Vayne tumbles, maneuvering to carefully place her next shot. Her next attack deals bonus damage.
Rolls a short distance. The next basic attack within 7 seconds deals 50/55/60/65/70% Attack Damage bonus physical damage, equal to 50/55/60/65/70% of total Attack Damage.

Silver Bolts

Cost: Passive
Range: 750
Vayne tips her bolts with a rare metal, toxic to evil things. The third consecutive attack or ability against the same target deals a percentage of the target's maximum Health as bonus true damage.
(Max: 200 damage vs. Monsters)
Every third consecutive attack or ability against an enemy deals an additional 4/6/8/10/12% of the enemy's maximum Health as true damage.Deals a maximum of 200 damage vs. Monsters and a minimum of 50/65/80/95/110 damage vs. all targets.
Condemn
Cost: 90 Mana
Range: 710
Vayne draws a heavy crossbow from her back, and fires a huge bolt at her target, knocking them back and dealing damage. If they collide with terrain, they are impaled, dealing bonus damage and stunning them.
Fires a bolt that knocks back target enemy and deals 45/80/115/150/185 (+50% bonus Attack Damage) physical damage. Enemies that collide with terrain take 45/80/115/150/185 (+50% bonus Attack Damage) additional physical damage and are stunned for 1.5 seconds.
Final Hour
Cost: 80 Mana
Range: 1
Readying herself for an epic confrontation, Vayne gains increased Attack Damage, invisibility during Tumble, and triple the bonus Movement Speed from Night Hunter.
Gains 30/50/70 Bonus Attack Damage for 8/10/12 seconds. While active, Tumble grants invisibility for 1 second, and Night Hunter's bonus Movement Speed is increased to 90 If a champion dies within 3 seconds of being damaged by Vayne, Final Hour’s duration is extended by 4 seconds. This cannot extend the remaining duration past the initial maximum duration.