Recommended · for some experience
#47 Power Saving with ESP8266 (Sleep Mode) Tutorial with some Tricks
Why people recommend it
Andreas Spiess covers ESP8266 sleep modes and measures its current spikes; cited both for low-power design and for why the module needs decent supply capacitance.
Watch for: start-up current spikes and light versus deep sleep
In their words
This video describes the spikes in details
Steven Smethurst on electronics.stackexchange.com, Feb 2017. CC BY-SA.
Again, this comment is getting too long, here is some info on how to implement it ([video])
H Ruiten on arduino.stackexchange.com, May 2018. CC BY-SA.
