A 4-layer PCB with a solid ground plane and thermal vias is recommended. Ensure that the thermal pad is connected to a large copper area to dissipate heat efficiently.
Implement a robust power-on reset circuit, ensure a stable clock signal, and use a reliable voltage regulator. Also, consider using a temperature sensor to monitor the device temperature.
Use a shielded enclosure, keep sensitive analog signals away from digital lines, and use a common-mode choke or ferrite bead to filter out high-frequency noise. Also, ensure that the PCB layout is optimized for minimal radiation.
Use the power-down mode, reduce the clock frequency, and minimize the number of active circuits. Also, consider using a low-dropout regulator and optimizing the power supply design for low quiescent current.
Monitor the device temperature, voltage supply, and clock frequency. Also, implement a watchdog timer and error detection mechanisms to detect and respond to faults.