A clear brief helps both parties estimate work and recognise when the project is complete.
Describe the result, who will use it and what is already available. For a landing page, list the copy, design files, access and required sections. Define the file format, review rounds and who approves the result. Include any examples with an explanation of what you like about them.
Ask for a short summary of the proposed approach before work begins. Use the first review to check the most important requirement while changes are still easy. Record decisions in the brief as the project develops.