Entities From a Sentence
Work from the brief alone. Write what you would produce — actors, requirements, data, a first slice, your unknowns — before opening anything below it; the exercise stops working if you read the reality first.
"A customer places an order containing several products, pays for it, and may later return some of them." Find the entities, the relationships, what must persist, and which fields must be snapshots. Do not draw a schema until the last step.
Your attempt
Nothing here is checked. It exists so that the reveal below is a comparison rather than a reading.
Drawing the schema first, from memory of every e-commerce ERD ever seen. It produces tables in five minutes, and one of them joins order items to products for the price — which is correct until the first price change, and then every historical order and every refund is wrong by exactly the amount of the change.
Read this even if you are confident. It is here rather than behind a button because it is the move most people actually make, it produces things that look like a project, and its cost arrives when the first hard requirement has nowhere to go.