This guide will teach you the proper order for jungling, skill uses, and Item Builds For lee sin, the Blind monk
UPDATES!
-Updated and added on Safeguard description
-Updated and added on Tempest description
-Changed Youmuu's Ghostblade to Last Whisper
-Changed Runes to Greater Mark of strength, Greater Seal of Resilience, Greater Quintessence of Resilience, and Greater Glyph of vitality.
Changes, Courtesy of Zell.

Pros
-Very good Ganking Capability with Resonating Strike
-Good Damage Early game
- Dragon's Rage can finish off and/or isolate Champtions
-He's Blind, and still kicks ***.

Cons
-Late game Damage may slow down and become less
-Requires much still to play, land and position Resonating Strike and Dragon's Rage
-A little quish early game
-He doesn't kick players off the map

Resonating Strike on of the best abilities Lee Sin has available to him. If you can Land Sonic Wave, then you have the ability to dash/kick your way to the m dealing damage. This ability is great for Ganking, if you can hit them with sonic wave, then a kill is almost guaranteed. a good strategy for placing sonic wave is to predict where the enemy champion is going to move next, so it can hit them when it gets there. Another important part of Sonic Wave/ Resonating Strike is to know when to kick and not to kick. It may be tempting to kick to a medium health champion with another champion around, but it probably will not be worth it, as you might be killed as you try to kill your enemy. You can also quick jungle with Resonating Strike by sending your sonic wave through a wall to hit a creep, then Kick to them without wasting time.

Tempest I pick this ability for jungling because the AOE damage early game is strong, and because of Cripple, it weakens creeps for easier early game jungling. Tempest can also be used to deal damage all around the enemy team widely, then crippling the hit champions so they become easier targets for your team. Cripple is a very useful tool for shutting down ad carries for a short time, buy lowering their attack speed,"crippling" them.

Safeguard This ability is amazing on lee sin. It can be used to dashed to use on wounded teammates, because the shield applies to both you and your teammate. It can also be used for a quick escape by dashing to a nearby friendly minion. A good Escape tactic is to buy some wards, and put them over a wall while you're being chased. From their, you can safeguard to the ward and escape safely over a wall. Safeguard can be used to save teammates in dangerous situations, such as if they were low health, and they ran into teemo's Noxious Trap safeguarding to them could save their life. It is also very important to know that safeguarding to a friendly unit will give both you, and the unit the shield so try to shield our fellow champions as much as possible!

Dragon's Rage An amazing ulti with a short cooldown. If you see a enemy low on health and you dash to her, make sure he/she has enough health to die, then kick them to oblivion. This ulti is very hard to place, because it kicks enemies backwards. Several times, I have saved enemies by using this ulti. you can also use this ulti in team fights, to knock a single target out of the battle disabling them, or Knocking them back into their team doing knockback damage.

Skill Sequence for Ganking: Resonating Strike -> Tempest -> Safeguard -> Resonating Strike -> Dragon's Rage

Skill Sequence for Escaping: Tempest-> Put down ward and escape to it by using Safeguard -> Dragon's Rage

I Take Flash and Smite for my summoner skills

Flash I take flash for its countless escaping and chasing capabilities. If you can't catch up to an enemy, then flash then Resonating Strike to them. Flash has saved me many times fro m death, but be warned, sometimes it might malfunction and you can end up flashing in place.

Smite I take smite for obvious reasons, Jungling. You can use this ability to smite buffs to make them much weaker for you to kill at early levels, and it might help you steal enemy buffs by running in and smiting a buff/ dragon/baaron etc. If you're not in the Jungle and get out to lane for a but, you can smite cannon minions for extra gold.

Optional Spells
Exhaust exhaust can me substituted for flash, It has numerous uses such as evening out a 1v1, or slowing enemies allowing you to catch up. Personally, I prefer flash, but Exhaust is also a Viable choice.

Cleanse Cleanse can be useful for escaping ganks, or if your enemy team has a lot of CC ( such as lux's Light Binding of Morgana's Dark Binding. It can be a substitute for flash for it's flexible capabilities

Ghost Ghost can be used to catch up, or escape from enemies. Ghost can be substituted with flash. Its a mattter of personal choice, so if you like ghost better than flash then take it!

No No's
Clarity Lee Sin does no have mana

Rally although it may have some use jungling, it just isn't a good enough spell to replace flash of smite

Promote Don't even think about it

Start off with a Vampiric Scepter for the lifesteal you'll need to jungle, then follow the following order of Creep Camps:
Start off With:
Wolfs
Wraiths
Golems (smite)
Red Lizard elder
Gank
go BTB to buy boots and/or wriggles
wraiths
Wolfs
Blue Buff
Gank
BTB for Merc Treads

Items:

after Vampiric Scepter, you'll want to get Boots

Next, I get Wriggle's Lantern. I get Wriggles for many uses. because of its Nice Balance of Lifesteal, Damage, and armor. The Unique active for wriggles, places practically a free ward anywhere, that recharges= free wards! It would not be worth it to sell wriggles for another item because of the ward/escape it gives you, which is invaluable.

Mercury Treads Because Lee Sin is an offtank DPS, he'll need the boots to withstand crowd control effects to get to his targets quickly, while doing tons of damage. The extra magic resist helps too, but the tenency is the main reason why Merc Treads are my main boots on Lee sin, helping him chase, and escape from enemies.

Trinity ForceTrinity Force Gives Lee sin Practically everything he needs. Attack speed, crit health damage, and an almost constant CC. although some might argue that the Sheen expense added into trinity force is worthless in Lee sin, the benefits are too much to give up.

Bloodthirster because the bloodthirster gives lee sin more vamp, and attack damage, it is a really viable item on lee sin, helping deal tons of damage while sustaining himself in battle. the Unique passive on bloodthirster works well on Lee, because since you're jungling, the stacks will add up quick as you jungle your way through the game.

Warmog's Armor I don't go full out dps on lee sin because he's just not meant to played that way. because lee sin may be a bit squishy early-mid game, warmogs is perfect with him, also obtaining permanent health and health regen per monster kill, which synchronizes with his jungling well, and makes him more sustainable in team fights.

Atma's Impaler The Combination of Atma's Impaler and Warmog's Armor is just too great on Lee sin. In addition to having additional armor and critical strike Damage, Atma's Increases Lee sin's Attack damage by 3% of your Maximum Health! a really big bonus to lee sin's damage output, while also remaining tanky.

Last Whisper I have replaced Last whisper for Youmuu's Ghostblade for a number of reasons. The Armor pen for the ghostblade was just too little (only 20) while last whisper gives you 40% armor pen, which is invaluable against tanks stacking up armor to counter you, and because of the decent damage (40) it gives you, which makes it a nice roundoff last item for lee sin.

I hope you find lee sin a fun and enjoyable champion to play, and I hope you enjoy him as much as I do (: