Hello There Summoners, the seaninator11 here!
Lee Sin is my favorite champion, especially to play in the jungle, and I thought I'd give ya'll a guide on how to play it well.
I start Hunters Machete+5 pots because that's just simply the best way to start any jungle in S3 (with the possible exception of rammus due to his passive). Start wraiths then red buff. If your teammates troll and don't leash you, start golems and use smite, then go wraiths, then take wolves and then head over to red buff and take it when your smite gets back up.
I get my W on lvl 2 because that way you will have much more sustain. Gank whatever lane is most viable to gank the second you hit level 3. Try to give your teams lanes and early advantage so they will be able to shut down the enemy team.
You can choose after you gank to give the blue buff to your teams midlaner/ap carry, so they will be able to get it much faster than their midlaner/ap carry and be able to spam you abilities more often. Preferably it would be somewhat good to kind of babysit the bottom lane though, so there adc will lose late game power.
Lee Sin mid and late game will most likely be playing the initiator for the team, since he has a decent gap closer (Q), which is why I build some tank items such as frozen mallet and locket of the iron solari. Activate your locket at the beginning of the fight!!
When taking out buffs with Lee, take two basic attacks on the big minion then press E. This doesn't make a huge change but this helps make sure all the buffs are really close to you so with your lifesteal and passive you will sustain much better.
Always try to have wards/wriggles in your inventory. One of the best things about Lee Sin is that you can jump onto wards using your w, instead of flashing the wall. You can also do what I think is the best kind of play other than a 1v5 that I've seen Lee Sins pull off. You can either set a ward and w to it or flash behind an enemy champion and use your ult and kick them back into the tower. Also make the best use of your ultimate by making sure your kick hits multiple enemies because when lee sin kicks and enemy champion back with his ultimate and the enemy hits another enemy champ, that champ is also knocked up. Ive knocked up the whole entire team with my lee sin ult and did 2v5 with a 0-2 rammus.
Most of all with Lee sin, enjoy the champion. Hes amazingly fun to play and with skill, I think hes one of the best champs in the game for a lot of positions.
Enjoy playing with the Blind Monk!