Most small businesses start with a spreadsheet column and a good intention. Then a job gets done on Friday, the sheet gets updated on Tuesday - and nobody trusts the numbers anymore.
The problem with manual stock
Manual counts are always behind. You quote for stock that isn't there, you reorder stock you still have, and you write off items that "should have been there". The fix isn't more discipline - it's removing the manual step.
Let invoices do the bookkeeping
The moment you sell something, your stock should drop. The moment an invoice is voided or corrected, it should come back. When the movement is automatic, your on-hand number is only ever as wrong as the last stocktake - not the last typing session.
Reorder levels stop the panic
Set a reorder level per product and you never have to "remember" to check. Anything at or below the level is flagged, so the decision to reorder is obvious, early and calm.
Keep a movement history
"Why is this product short?" is a question you should be able to answer. A simple audit trail - sold, adjusted, restocked, voided - turns a mystery into a fact in seconds.
On Pro, enable "track stock" on any product, set a unit and reorder level, then watch levels move as invoices are created or voided. Low-stock items are flagged on the Inventory report.