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.
Establish ownership rights to the work. Even in service situations, a product is sometimes the result of the work, so you should also include which party retains ownership rights. For example, the copywriter can state that she turns over all rights to the writing of the brochure to the customer and that she makes no claims of ownership to the writing once the customer pays for the written product. Add signature and date lines. Be sure to provide a space for each party to sign and date.