So when I began playing LoL I was a 
main but that was so long ago (1 year 5 months ago)
So how does the jg work now after all this changes?
What should I smite early game?
Invade?
Where to gank?
I also want to begin to play Lee Sin 
any tips/builds for him?
Always start either Gromp or Krugs, whichever your bot side is on. Smite it first.
That first camp will give you level 2, and 2 more camps will give you level 3. 3 more camps after that will give you level 4. So in one rotation you should be level 4.
On Lee Sin, start with your q and max it first. Max w after your q, then max your e. If you want, put a second point in w at level 4. That's if you think you will be fighting dragon.
Cinderhulk and Warrior both work on him. If you can land a skill shot then you are pretty solid on Lee Sin, and Q+R+Q is a good nuke.
Red Buff is really strong buff on Lee Sin, and it helps you take turrets faster.
When farming with Lee Sin, use your passive (2 auto attacks after each ability), save your resonating strike (Q2) until 2 seconds after you used sonic wave, and make sure you are casting w on yourself frequently.
Ganking hasn't really changed, but it's easier with red buff because that applies an on-hit slow.
