Turn off raspberry LEDs, save power, energy, disable wifi, bluetooth

In general add these to /boot/config.txt

echo "# Disable the ACT LED" | sudo tee -a /boot/config.txt
echo "dtparam=act_led_trigger=none" | sudo tee -a /boot/config.txt
echo "dtparam=act_led_activelow=off" | sudo tee -a /boot/config.txt

Disable power led:

echo "# Disable the PWR LED" | sudo tee -a /boot/config.txt
echo "dtparam=pwr_led_trigger=none" | sudo tee -a /boot/config.txt
echo "dtparam=pwr_led_activelow=off" | sudo tee -a /boot/config.txt

Disable Ethernet LEDs:

echo "# Disable Ethernet LEDs" | sudo tee -a /boot/config.txt
echo "dtparam=eth_led0=14" | sudo tee -a /boot/config.txt
echo "dtparam=eth_led1=14" | sudo tee -a /boot/config.txt

Disable wifi:

echo "dtoverlay=pi3-disable-wifi" | sudo tee -a /boot/config.txt

Disable bluetooth:

echo "dtoverlay=pi3-disable-bt" | sudo tee -a /boot/config.txt

Disable systemd service that initializez Bluetooth Modems connected by UART:

sudo systemctl disable hciuart

Disable onboard audio driver:

echo "blacklist snd_bcm2835"> /etc/modprobe.d/alsa-blacklist.conf

To save more power can cut the TV service:

/usr/bin/tvservice -o

Related:
https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README#L96%E2%80%8B