Vayne guide!

As Vayne your early laning phase is very weak, I will always try and last hit as slow as possible, sitting far back, and let the enemy push on me, it allows your jungle to gank so much easier, and keeps you relatively safe from free damage.

You should be able to last hit under tower once you get a feel for the tower rhythm, and if your jungle ganks your lane while the enemies are over extended, it can really help you turn into a powerful laner, so you don't need to be so passive any more.

Against almost every AD carry, and support combo (I know this sounds crazy!!) , Vayne can go all in at 6 as long as she is full hp, the enemies are over extended past the mid of the lane, you land condemn, and you have shopped up to par of the enemy recently.

Vayne just has so much sustained damage, and damage mitigation from avoiding abilities/enemy attack animation with your ult its hard for people to exchange up to par with her, and can usually knock the enemy out of lane, or secure a kill, just got to be careful against, say Graves, or Ezreal to not get hit by their skill shots, over time you should figure out how to dodge them as effectively as possible.

Vayne is one of the harder champions to team fight with because she is 100% reliant on positioning, but once you master it she is in my opinion the strongest AD carry in the game, a lot of the time I would suggest just attacking the closest target to you, but some situations you can dive right into the biggest threat, and assassinate them, you just need to make sure their front like, say Cho/Ali/Malphite/etc have used their CCs on other targets, and won't be able to shut you down so their carries can burst you as soon as your stealth breaks. Vayne requires a lot of awareness/timing of yours/enemies abilities to use right in a team fight, and a lot of it requires experience, you don't always need to land your condemn into a wall on a carry either, it is GREAT for peeling a bruiser off of yourself or even a ally in trouble while you kite, or dive into the enemy carry.

One of my favourite little tricks with Vayne is just staying in lane and pushing with limits. If you're half hp, enemies are full with cooldowns up, chances are they will try to dive you. Don't do this if your summoners/ult isn't up, but there is NOTHING more satisfying than out playing the enemy when they try to dive you, cleanse their CC/exhaust, flash to the side of their AD, condemn him to the wall, attack him a few times, pop ult, tumble when he is not stunned anymore, and just go ham on the guy, it catches people off even in 2000+ elo, and works over half the time if you are great mechanically, and pull off the situation perfect.