Quick answer
A POS system is judged on one thing: whether you can keep billing when something goes wrong. Everything else is convenience. Plan around the failure cases and the rest follows.
The printer is the part that fails first
Thermal receipt printers are consumables with a motor in them. A cheap unit in a busy restaurant will start dropping lines within a year, usually mid-service. Buy a printer rated for the volume you actually do, keep a spare roll within arm's reach of the counter, and keep the old printer when you upgrade instead of discarding it.
Decide what happens when the internet stops
This is the question that separates systems that work here from systems that were designed elsewhere. If your POS is entirely cloud-hosted with no offline mode, an ISP outage stops billing completely. Either choose software that queues transactions locally and syncs later, or keep a manual fallback that staff have actually practised.
- Local billing with cloud sync: keeps working through an outage.
- Cloud-only billing: fast to set up, stops dead without a connection.
- Whichever you choose, test it by unplugging the router during a quiet hour, not during a rush.
Cash drawer and connection
Most drawers open from a port on the receipt printer rather than from the computer. That means the drawer is tied to the printer's health, and a printer swap needs the same port type. Check this before buying either part separately.
Power
A small UPS covering the terminal, printer and network switch costs less than one lost evening of billing. In practice this is the single highest-value addition to any counter in Kathmandu.
Backups you can actually restore
Ask a direct question of any POS vendor: if this machine is stolen tonight, what do I have tomorrow morning? If the answer involves a file on the same machine, it is not a backup. Sales history, item masters and tax records should exist somewhere else, automatically.
Test the restore, not the backup. A backup nobody has restored is a hope, not a system.
Tell us what you have already tried. That helps our technician arrive prepared.