Your customers and suppliers live in separate registers with all history gathered. As with products, it pays to think in categories from the start.
Why categories help
Reports can be grouped and filtered by customer type or supplier type.
Default settings (e.g. prices, payment terms) can be set per category instead of per actor.
Overview in a growing customer base becomes much easier.
What you need to decide
Whether you want to distinguish between e.g. business and private customers.
Which supplier categories make sense for your purchasing.
Read more in Customers, Suppliers and Actor setup.