This paper presents an approach for the implementation and execution of an effective requirements generation process. We achieve this goal by providing a well-defined requirements engineering model that includes verification and validation (V&V), and analysis. In addition, we identify focused activity objectives and map popular methods to lower-level activities, and define a criterion based process for optimizing method selection for attendant activities. Our model, unlike other models, addresses the complete requirements generation process and consists of activities defined at more adequate levels of abstraction. Furthermore, our model also incorporates a unique approach to V&V that enhances quality and reduces the cost of generating requirements. Additionally, activity objectives are identified and explicitly stated - not implied as in the current models. To assist in the selection of an appropriate set of methods, we have mapped commonly used methods to activities based on their objectives. Finally, we have identified method selection criteria and prescribed a reduced set of methods that optimize these criteria for each activity in our model. Thus, our approach assists in the task of selecting methods by using selection criteria to reduce a large collection of potential methods to a smaller, manageable set. The model, clear mapping of methods to activity objectives, and the criteria based process, taken together, provide the much needed guidance for the effective implementation and execution of the requirements generation process.