Lee sin is bruiser with amazing burst and strong early game/mid game. He has really unique kit with many gap closers and escapes. Most amazing part of him is that he has 2 abilities in 1 ability =). And is champ that needs lots of skill and practice. Don't play this as your first champ. Lee sin works in jungle too and I love to play him there but this guide is for top lane

Not anything special **** in masteries go with 21/9 for early damage or 9/21 if you are not so good with lee or if you want to be just more tanky.

REDS: 8 AD reds and 1 crit because it is so awesome if you have good luck =).
YELLOWS: Armor awesome against AD top and even against AP it helps really much
BLUES: Scaling magic resist or flat if you are against AP top
QUINTS: 1 AD quint for damage and 2 lifesteal quints for sustain

PROS
+ All abilities help him to escape
+ Awesome burst in early game
+ Awesome chaser
CONS
- Falls of late
- Hard to master

Passive: Gives you attack speed it is good in early game but not so great in late game because you are more like AD caster

Q: Awesome escape and does crazy damage early, but is hard to hit to mobile enemies from long distance

W: Gives you good sustain and is awesome escape and helps your ganks when roaming

E: Slows does damage reveals and slows attack speed pretty simple. REMEMBER scales with AD

R: His ult is really amazing you can knock enemies in your team. And do the popular InSec kick if you don't know what it is I tell it later in this guide. Still this ultimate can knock full enemy team in ait and does heavy damage and scales well with AD.

Main kill combo if enemy is fighting against you in melee range is to throw your Q then press R and again Q and then E.

When ganking jump with your W to minion or ally champion then hit you Q to enemy jump with Q then kick enemy to your teammate with your R.

InSec kick is when you jump in with your Q put ward behind enemy jump to ward and kick the enemy to your team

When playing Lee sin you can max any of your abilities first but it depends of your opponent.
Q: Max when you need damage works well against other AD casters/bruiser with small poke or tanks with small poke

W: Max when your enemy has large poke or good sustain

E: When your enemy has high attack speed and main damage comes from auto attacks like tryndamere.

You can farm/push well with your E and hydra/tiamat active

This was second guide but my first guide was pretty bad and I made this guide for sometime hope you like it. I'm not really good at League of Legends I'm in silver only but I hope this guide helps you lot.