In general Vi counter all tanks, because of her hard armor penetration W passive. Also she destroy all Champs without stuns or slows. Vi is a very mobile jungle champion! So you can gank a lot. And if you are feeded, you can kill every champion! all the same whether he is a counter or not!

You have to decide which runes you prefer. If you want to have a bit sustain in Jungle, take the Life Steal Quints. When you only want to have more Ad on level 1 tanke the Attack Damage Quints. But finally its your decision.

Vi is a jungle champion with not that much sustain. She have shield which can hold 2 or 3 autohits from blue. In Jungle you start skilling your E or W. If you want go gank with level 2 you skill E first and than Q. If want to gank later start with W and than E. Your first gank on level 2 or 3 have to be a good one, that you level up! With Vi you should start with Blue but dont smite him! Than you go smite Gromp. After you go kill Red, than go back! And after that you can gank. you also can gank after blue when you are level 2 and skill your Q.

You have to Choose, with role you want to play in the Game! If your team have only one Tank you can play the AD Offtank role. If your team have two or more Tanks, you should play a AD carry role! If your team haven't got a Tank, you better go build Tank. Its important for Teamfights, that you build the right items

You are the 2nd who engage! Just go in with your Q and try to knock up many as possible enemies! If you want to focus out someone, use your Ultimate R first, than Q knock up and E for damage. You're a strong CC champ: dont let your team fight without you! And in early game you have to gank a lot! Later, when teamfight starts, you go on a lane and farm. You need your Stalkersblade, mercury's Treads and sunfire cape to are usefull in Teamfights!

You let your Team engage and wait that all enemies have less than half life! Than you focus out one. And first kill one, than your try to kill the next. And so on. But DONT jump in and attack all. Try to fight only 1vs1 fights, or if you are feeded 1 vs 2. If you dont can kill anyone escape with Q or focus someone out with your ult! If you want to play this build, you have to gank a lot in the early game.

The Tankbuild is a simple build, but is realy strong in teamfights! You have to engage with your Q or R. And you have to stay in, as long as possible. You should'nt jump out while one of your teammates is there and fight with you. You dont need much feed to build tank! If you are not feeded, build first the tank items and lastly trinity force.

Sorry for my bad english. I am german and my english isnt the best i used google translator to make it more understandable. If you want a German blog wrote in comments please!
I hope my guide can help you.

by Lurkep1 :)