You may want to have an attorney review and make suggestions on a template of your business contract. An attorney can pinpoint issues for your particular business that you may need to include in the agreement. You can use a business agreement template and modify it to fit your needs, rather than writing the agreement from scratch.
Describe the other party's obligations in detail. In the case of out brochure writing example, this might explain that the client is responsible for providing the copywriter with business information in a word processing document to describe the business and the information to be included in the brochure text.