Learning Lee sin, build and mechanic tips.

Hello everyone,

I just came back from being absent over a year and decided to pick up lee sin again. I have recently begun to play him heavily knowing full well that he is one of the stronger champions. I can play rengar and fiddlesticks extremely well however when it comes to lee it seems that i just feel his damage is not all the way there. After i get the spirit of the elder lizard do i rush Hydra or randuins etc? Usually early on besides my last game i was very far ahead but fell off midgame due to i believe poor item choice. I was wondering if anyone could recomend a build path besides the Spirit elder lizard, boots, Hydra due to fact hydra seems to delay the much needed midgame power spike that i am searching for. Also what items should i be optimizing on lee and how the heck do people drop dragon from 1/4 health to 0 as him instantly? Ive tried the smite, q,q but it just doesnt seem to do that much dps.

Any help to a returning player would be much appreciated.