1. What actually matters in counter staff
Product knowledge can be taught and arithmetic is done by the software. What cannot be taught quickly is reliability, willingness to say "I do not know, let me check", and a manner with customers that does not lose them. In a material shop, the person who remembers that a contractor asked for something you did not have — and tells you — is worth more than one who bills faster.
2. Agree the terms in writing on day one
Four things: the monthly salary, what counts as a working day and what counts as half, whether overtime is paid and at what rate, and how advances will be adjusted. Almost every salary dispute in a small shop comes from one of these never being stated. Writing them down takes ten minutes and removes years of friction, and it protects the staff member as much as it protects you.
3. Give them a limited login in the first week
The instinct is to keep everything to yourself and let staff write slips. That guarantees a second record and guarantees it will not match. Give a new person billing and receipts only, and add permissions as they earn them — starting broad and pulling back never happens. A staff member who can complete a sale unaided is the point of hiring one.
4. Train on the ordinary sale, not the whole system
Teach the sale they will make fifty times a day and nothing else on the first day. Adding a party, taking a payment, printing a receipt. Everything else — returns, quotations, reports — can wait until the basic transaction is automatic. Most counter staff are billing unaided after one session when the training is narrow, and overwhelmed after three when it is not.
5. Watch the first fortnight, and say you are
Look at the audit trail and the per-user day-end for the first two weeks. Not to catch anyone, but because early mistakes are training gaps and finding them in week one costs far less than finding them in month three. Tell the person the trail exists on day one — it reads as normal then, and as suspicion later.
6. Why people stay
In a counter trade, continuity is worth more than the salary difference between one candidate and another. People stay where the arrangement is clear, the salary arrives on the same date each month with the working shown, advances are handled without embarrassment, and they are trusted with something. All four are ordinary management, and all four are why the shop down the road keeps losing staff and you do not.