To prepare a Quality Assurance plan for an app, you should start by identifying the scope of the app, its intended audience, and any specific requirements or regulations that must be met. Next, you should define the testing strategy, including the types of tests that will be performed, the tools and resources that will be used, and the roles and responsibilities of the testing team. Finally, you should outline a timeline for the QA process, including milestones and deadlines for testing, bug fixes, and release dates.