A good way to ensure efficient and effective requirements and to design artifact approvals is to plan for the approvals, the method, and the format that will be used and the people who will be required to approve them. It is important to consider the type of project you are involved in—for example, is the project very structured and governed by the organization or is the project being run very flexibly and quite informally? This will help you to determine what format and structure your approval processes should take. 

In a very controlled or complex environment, it will most likely make sense to have a formal and well-defined approval process for the requirements and designs. However, in a more informal environment, a structured walkthrough showing example prototypes might be all you require in the form of approvals. It is, however, very important to confirm early in the project, while you are carrying out your business analysis planning and monitoring activities, what the most appropriate approval processes should be in your specific situation.