Vi definitely isn't the best jungler, but she is good with her wall jump for ganks and her armor shred. Gank often while playing Vi and know how to do it. Q first to enter lane and hit an enemy with it. this can work well if you hit them into you're turret(her Q knocks back an enemy hit with it) and also use it for escaping through walls. Vi doesn't need Flash what with her Q, but it is recommended. Try to have wards at their Red buff, and their blue buff if you plan on invading(i recommend it) and always ward you're own buffs too. ward the patch of grass near the dragon frequently, one at a time for all you noobs out there.
Ward baron as soon as it comes up. Good times to ward? ALWAYS. There is never a bad time to ward, and it is always just about necessary.
That's just about all there is to remember when playing Vi. Just Leave the sound on to hear turret shots and Vi's amazingly funny jokes. She's an overall moderate champion to play. however she's only useful jungle right now, so remember that shes not always a good idea.

She is a very fun champion to play jungle. she starts blue buff and then you kill wolves and go straight for red buff. you then should just clear any possible camps and always keep moving. never stay still even for 2 seconds. One is allowed sometimes to type, but be cautious the jungle is dangerous my friends :).

Vi works well with a ranged champion like Caitlin. She excels at moving quickly through objects and can take advantage of a ranged character's abilities. Ashe and Cait and Varus and Lucian are all good choices to team up with. Never lane with Vi as it does not end up well for her. She also has a hidden passive when playing with Cait called Piltover's finest.
She works very well with any champion that is fast enough to keep up, otherwise she'll overextend and she'll be massacred by a team of enemies. Her E is always a good choice in abilities for teamfights as it deals damage to those behind her target. It can also be used as a poke, but be cautious. any champion with a pull easily kills this strategy unless the pull to you.

DON'T do this in lane. Let you're team get the kills, minion kills, and last hits. try to get assists. you still want to be fed though, so if the enemy is alone when you gank and so are you, it is ok to do these things, otherwise, avoid them. Get the kills only if they try to run and you're team cant can't catch them.

Try not to if at all possible. only juke the tower if you would die from the turret's shot. Use you're E to give a shield from her passive to absorb some damage. this ability is increased late game. Tank Vi works very well for tower diving. A juke is a quick getaway without a chance of being caught by the way for those noobs.

Vi gets her red buff first and she then kills wolves. Try to get a leash for getting blue buff, but nothing after. Kill blue buff with smite and then kill wolves. Then head for red buff. Smite it too and then go ahead and gank whatever lane you think need it. Back off if they tell you to though. Then I advise backing and buying you're next item(s) and then going to gank another lane or simply jungle farming. Don't gank if you're team is wrecking the lane, but if they are either doing ok, or plain out getting mauled, GANK FOR THEM.
When you are level 8 or 9, you may be able to take dragon solo. If you do, ward the area beforehand and then when you kill it run fast through jungle towards you're base. If you're on blue team you'll have an easier time of it, but its still simple on purple team.
NEVER try to solo baron until level 18, and even then, bring a friend. ward ,the area heavily. river especially and both buffs if you have time. Try to make sure they don't have it warded too. Sweeping Lens or Oracles lens will help, but if you cant, then just be wary. try to smite it and get the kill as it gives a lot of experience. Red buff and Blue buff are two good things to have during a baron steal. At a medium level, you can try to pentateam baron, but it is still risky. Any dead teammates will not receive purple buff, but they will still have an advantage with the rest of the team being stronger.