Make each item understandable
Give the item a recognisable name and describe what the customer receives. Define whether it is sold per hour, per unit, per project or on another basis. Keep internal notes separate from the text intended for a customer. Review prices and relevant finance settings with the people responsible for them. For a service, useful descriptions often explain the included work and the assumptions that affect the final scope.
Control changes to commercial information
Decide who can maintain catalog entries and when a changed price should take effect. An updated item should not create confusion about a proposal or invoice already agreed. Avoid creating a new near-duplicate entry every time a customer needs a small variation; use a considered naming and review process. Where inventory or an accounting connection is involved, agree the identifiers used to match the same item across systems.