I still forget to put static defense down all the time.
Spores are definitely good but on top of that - map vision is one of your biggest weapons as a Zerg. On some maps it's difficult (**** you Heavy Rain) but on most maps you can get overlords spread such that with good minimap spotting (if you don't look at the minimap, like, all the time, LOOK AT THE MINIMAP ALL THE TIME) you will see drops incoming well before they're at your base. Then you just a-move your muta ball and laugh as full medivacs explode out of the sky. It's really ****ing satisfying.
Here's an example for me, on Yeonsu:
Between these overlords, controlling the watchtowers with a ling at each (and taking them back if Terran gets uppity with me), and creep spread, they ain't doing **** to me that I'm not gonna know about well in advance.