My actual Seals I couldn't include because Moba doesn't have energy regen in the list. So obviously I put mana regen to make up the 30 runes criteria. This is what I actually use for them though.
5x Greater Lucidity
4x Greater Meditation

This is a build I decided on when I went back to playing Lee. After not playing him for ages I carried my team with a 9/0/13 score. Not only was I out-putting heaps of dmg (even to morde) but i was also almost indestructible. You need to make good use of your Safeguard/Ironwill, which is what the energy regen seals are for. This one skill can easily change the game, especially if you're fast enough to shield people from dying. I've used Safeguard to shield suppressed allies in Warwick's ulti, then dragon rage kicked to resonating strike followed by tempest and he's dead.

Looking at the Lee Sin recommended build made me depressed. :D
Why would you want to take items that give to mana (Banshees+Trin Force) when Lee has no mana? This to me seems like a total waste of two items. There was so much potential in Lee to be totally awesome, so i set about to figure out how that could be achieved.

The Madred's Razor is the big piece of this build. With it you're strong enough to take down even the toughest tank. The Bloodthirster and Blackcleaver are nice little additions to this for extra dmg. I chose Spirit Visage for the health/regen/magic resistance, and the Randuin's for armour and health/regen again, plus it's active slows enemies for some nice skill combos.

In order to be effective and fully utilize Lee to his highest capability you need to constantly be watching for allies that need safeguarding, keeping them alive long enough may be what changes fights for you. If you lane with a healer, being healed and safeguarding the healer constantly works nicely. When in team fights try to get in amongst it, and don't stand around at the back waiting to get kills. With properly timed safeguards and Tempests, you can do a lot of dmg right in the middle of a group fight. Try to use dragon rage to get rid of enemies rather than doing dmg or getting kills. Lee's ulti is most effective when they are grouped up close, this way his kick knocks them all up, allowing you and your team to bring the hurt while they're stunned.

I take Ghost and Exhaust

I have played Lee successfully in mid. His Safeguard is a great tool for shielding you and getting back health. Up until about lvl 4/5 just focus getting last hits, then when you get Res Strike, use that to jump in and harass your opponent, then Safeguard back away from them. This together makes an excellent tool for keeping your enemy away from their minions. Res Strike to them with a nicely timed Tempest to follow, then Safeguard back to a minion or ally and you just took 1/3 to half their health off. The armour pen marks are integral to this working properly. Before you get your Madred's, you may feel like some ranged enemies are hassling you a little too easily. Just stick it out, trust me it gets a whole lot easier when you have your Razors. Just make sure to Safeguard your health back whenever you can and you'll be fine.