Before you sell the first item, there are a handful of things worth getting in place in the right order. A good setup from the start saves you cleanup and errors later.
The order we recommend
Chart of accounts — the foundation of the entire accounts.
Finance setup — VAT and posting rules, before you post anything.
Product register setup — categories that drive inventory, accounts and reports.
Inventory method — choose the method before you start keeping stock.
Customers and suppliers — registers and categories.
Prices and discounts — the base model for pricing.
Users and access — who may do what.
Integrations — webshop, payment and bank, once the rest is in place.
Each item has its own article here in "Prepare your solution" that explains *why* it matters and links on to the detailed guide.
The first items — especially the chart of accounts and finance setup — have a big impact on your accounts. If in doubt, do them together with your consultant or accountant. It is easier to get right from the start than to correct afterwards.