When I first played Lee Sin, I played him as a Solo Top champion, but I didin't like it that much, maybe it was because of my Q that went all the way from top lane to bott lane, due to the teleport from the enemy, anyways I played him as a jungler and i completly loved him, so i decided to make a guide for Lee Sin players.

The reason why I chose these runes are:
1st- Attack damage marks and Quintessences, I always feel like I don't have enough damage without these marks, and because of Lee Sin's passive you don't really need AS runes.
2nd- Armor seals, it gives you more resistance against AD champions and obviously minions and neutral monsters which allows you to lose less HP and farm more aswell as gank more.
3rd and final- Health Glyphs, for the same reason then the armor seals, more survivability.

Note- Of course if you see any of these runes that don't fit your playstyle you can always change them, it's my opinion.

Offensive Masteries - Lee Sin has already alot of early game damage with these runes so I don't feel necessary to waste masteries on more offense.

Defensive Masteries - Lee Sin isn't much of tank champion, when he first came out, he would die easly even if he was full tank build, so i decided to play him more in defensive masteries.

The items that I chose, give Lee Sin an early game tankyness and damage but you can change them.

Boots - The boots that you buy is really an enemy team based choice, go for Mercury Threads if you see to much Crowd Control on the enemy team aswell as a fed AP mid Laner :)/ If you see that they have too much AD on their team go for Ninja Tabi, and so on.

Wriggle's Lantern - Obviously a crucial item for junglers, due to its life steal and a chance for 425 magic damage on minions which grants you a faster jungling, also you get a ward every 3 minutes :)

Phage/Frozen Mallet - This item gives you a health, attack damage and a chance of slowing an opponent(which is good for chasing and ganking), if you go with Frozen Mallet like I pointed in the build you get a permanent slow on the enemy you are attacking.

Warmog's Armor - Just to give you more sustain and health, synergizes well with Atmas Impaler due to its amazing health plus the bonus health per minion kill.
Atmas Impaler - It gives you armor, critical chance, but also gives you attack damage for the percentage of health that you have, and 3.6k health grants you alot of AD.

Last Whisper - It gives you armor penetration and attack damage, which makes you deal alot of damage even to targets who build armor.

Guardian Angel - Obviously makes you stay longer in team fights and tank more due to the second chance of living that it grants you.

Optional Changes:

Bloodthirster - If you don't feel like you have enough attack damage and life steal, go for The Bloodthirster.

Infinity Edge - I don't usually buy this item, only when i feel confident to deal damage and take down opponents fast in late game.

Thornmail - If the enemies AD carry and meele are dealing ''tons of damage'', obviously only Ninja Tabi is not gonna be enough, go for Thornmail to smash their faces in pure steel.

Force of Nature - If the enemies AP mid laner is dealing more damage than you expected go for FoN, gives you a nice magic resistance and a nice health regen.

The only spells that I like to use while playing a jungler like Lee Sin, are Flash(or Ghost) and Smite.
I don't use exhaust because your Q grants you great mobillity and it's easy to reach your opponent if you pratice your aim, once you are near them, red buff and your E will give you the slow you and your laner need to catch up.

Start with E and head to wraiths, ask your mid laner to leash the Wraiths and pull the Red Buff, once that's done, unlock Q and go gank if you feel confident and you see possibilities.
Head to the Minor Golems, once those are dead head over to the Wolf Camp and to Blue Buff, I don't usually give the first Blue Buff to the mid laner, i tend to give them the second one.
At lvl 3/4 a gank should be certain, head for the lane that you think the enemies have pushed the most and are more open, if you see an enemy ''asking to die'' never hesitate, always ask your allies for Enemy Wards and summoner spells like Exhaust, Ghost and Flash.
The second Red Buff should be up at around 7:15 into the game, once thats done ask your team mates to push the lanes and head to Dragon, take caution of Enemy Wards, the Dragon respawns 6:00 later, so keep an eye out for the clock.

If you see enemies attempting dragon, place a ward out of the Dragon's Place, be sure to have Smite ready and Flash Ready, when you see the chance, land your Q on Dragon, use Q again and try to smite steal it, if you don't get it walk to back and use your W through the wall onto your ward that you placed, use flash if necessary.