Update, and keep updated. Many things change in both hardware and software and Google is correcting issues that arise. By keeping the OS up to date, you can be proactive in preventing downtime.

Powerwash (CTRL+ALT+SHIFT+R at main login screen) or (ESC+Refresh + Power button, then CTRL+ALT+d) is another valuable tool that can clean existing profiles and can fix issues with software and hardware. Student data will not be lost as it is saved in the cloud and will download the next time they login.

Hard Reset (Refresh + power button) can correct issues with hardware or a locked up unit.