As Vi you always have to get good ganks for your teams as your the person who burst damage on their champs. You always engage team fights because of your Q+R combo onto the adc, because you are really tanky with the items you get. But if you get killed bunch of times don't afk because i felt like that many times. Just go back to jungle get gold then buy items, you will never be behind if you do your job as jungler supposed to do :) Make sure you always have vision on dragon!

You don't back from your jungle until you can purchase your first items, I usually finish my first 3 camps and look for a mid lane pushed out for a good gank. If successful you back and buy the items. Always try to get the Rift Scuddle Crab for vision in Riven for all lanes. I don't invade as Vi in early game because you can get easily killed.Blue side
1. Start Golems (hard leash) meaning you use NO smite.
2. Red buff use Smite
3. Wolves
4. If you have more then 3/4 of Hp look for mid lane gank if the lane is pushed out.
5. Rift Scuddle Crab for vision for lanes
6. If mid lane gank didn't work look for top gank.
Red Side
1. Start Grump (hard leash) meaning you use NO smite.
2. Blue Buff use Smite
3. Wolves
4. If you have more then 3/4 of Hp look for mid lane gank if the lane is pushed out.
5. Rift Scuddle Crab for vision for lanes
6. If mid lane gank didn't work look for bot gank, make sure you target ADC and let the team know you going in!
This is my route I do when I play Vi either starting top or bottom of map

Pros:
+ Strong Late Game
+ Burst Damage with Q+E Damage.
+ Can Target ADC with your R.
+ Good Sustain in jungle.
+ Good Team fight engage.
Cons
- Vulnerable without Q
- Can't invade, only if you mastered the Champion.
- Easily can get picked off by ranged Champions.

If you have played a lot games with Vi you can try this Skill that I personally do when someone is trying to escape or there is a wall between. Try to hold Q and wait till its maxed range then flash towards the champion running then release for the hit. Then E + R so your team can catch up while you have the champ pinned. It's hard to manage to do but really good if you have your team on your back :). Practice this in normal games then you can try it in ranked :P Also Use your Q ability for escaping to save flash for really bad situation.