Lee sin is a strong early and mid game jungle. As a jungle you want to gang early very often and put pressure on enemy jungle! You want to get objectives and look for 2v2 fights as a bruiser and 1v1 as an assasin.

As a late game strategy you want to be more tanky and survive longer in fights. You won't be doing too much damage but your ult can be very usefull in teamfights.

As a mid laner you should go for an assasin build. You start E for wave clear and look for easy roams once you push. If you have hard time with your lane just stay and farm up until you buy a mythic item and look for a kill!

This is an optional tab! Here you can understand how does your champion actually work.We can start with the clear path: Blue buff, Gromp, Wolves, Raptors, Red Buff, if you want you can do Krugs too, then scuttler. Smite on Gromp and Red Buff. Refillable on Raptors and Krugs. You can also path red to blue side depends on which side you want to gang. In your clear you should always use your passive: Between every atack try to hit 2 AA, so you can get the best value of it.Gangs early on bot can go pretty bad as of their CC so be carefull. Top lane or mid lane is better as you can even get first blood. Champions like Lilia and Evelynn should always be harassed in the early game.
Lets talk about runes:
Conqueror: Easy to proke, because of your poke and good synergy with the champion.
Triumph: Great synergy with the bruiser build.
Legend:Alacrity: Gives Atack Speed which goes great with Lee Sin's passive.
Last Stand: Best synergy with goredrinker, if this runes are played with assasin build it is better to use Coup de Grace.
Inspiration: Great tools to complete his early power in-game
Magical Footwear: If Lee Sin gangs a lot he can receive them earlier than 12 min and get more gold for his next items.
Cosmic Insight: Gives a lot of Ability Haste which Lee Sin can use a lot in the early phase of the game to complete his power!
I recommend this rune page as it is perfect with Lee Sin's kit and standard build. The assasin build and runes are relying too much on snowballing and winning by getting a lot early advantage which sometimes can be hard.
Electrocute: Grest synergy if full combo(Q1,Q2,,E1,E2,R) is hitted.
Sudden Impact:Great with mobility champions.
Eyeball Collection: Gives more AD and helps with the snowball kind of style.
Ultimate Hunter: Gives Ability Haste on your ult and it goes great with the assasin build.
Precision: Just for exta sustain and damage
Triumph: Good in 1v2 situations and when ignited or burned.
Coup de Grace: Great synergy with the assasin build.
Assasin is very often relying on teammates,wave's position, great roames, and doing almost no mistakes. Snowballing is great, but it comes with the risk of falling behind.