Lee Sin can very easily proc Electrocute as his [Q] counts as 2 unique spells. A quick auto after [Q] and Electrocute will go off immediately.
Dashing with either [Q] or [W] makes for an easy way to get a quick 10 Lethality, giving Lee plenty of early game kill potential.
Snowball is the name of the game with Lee, so early kills/assists give Eyeball Collection even more power granting Lee additional early game damage.
Zombie Ward is also a great option thanks to the nature of your ward spamming.
Lee greatly benefits from *finding angles with high movement speed. Scrapping for early game kills/assists gives Lee the ability to find those angles with Relentless Hunter.
Cooldown Reduction allows Lee Sin to further scrap in skirmishes, enabling multiple spell rotations. Transcendence allows him to get some early CDR for free and not punishing him for continuing to build it if need be.
Waterwalking further promotes Lee's ability to find angles for fights with movement speed. It pairs very nicely with Relentless Hunter.
If you're playing into a heavy burst mage mid and AP Jungler (like Elise), Nullifying Orb might be a better option here.