Lee Sin looks too complex for my brain, like I GET what I gotta do, but I'd fail terribly at applying it XD.
Will try him for shits and giggles, maybe against Intermediate AI?
I've made a build for him I think which is mainly Attack dmg+defense+mag res and at least 1 lifesteal, cuz I'm sure I've seen a few Sin's who used Lifesteal with him.
IKUO MUTHAFUCKA!
Things to know for jungling Lee:
You can Safeguard yourself while fighting jungle camps to generate the shield, attack speed buff, and the Iron Will activation. Particularly early on, you want to space your ability usage to maintain uptime on your passive attack speed buff. So, for example, you can Safeguard -> Auto -> Iron Will -> Auto -> Sonic Wave -> Auto -> Resonating Strike. (You actually get two sped-up autos per ability but beyond Lv2 you probably won't actually spend enough time fighting camps to use all autos, you just want the one for Energy refund.)
If you're low on health while clearing Safeguard -> Iron Will -> Smite -> QQ in rapid succession is your best friend. The Iron Will gives you extra lifesteal/spell vamp, the smite gets the target low, and Resonating Strike capitalizes for good refund of life. You miss out on the Energy refunds of weaving autos this way, but it gives you a quick burst of life and should be all you need for Wight.
Once you get rolling don't forget you can use Sonic Wave long-range to "tag" the big mob in a camp to get there quicker with Resonating Strike, especially over a wall. You have to move around the map pretty fast as Lee Sin to capitalize on your early game advantage as much as possible.