Let the Use Case model reveal information
A void analysis paralysis by not trying to be right the first time through. It just is not possible.
Allow for a number of passes through the problem. Move on to other models and revisit the use cases after digging a little deeper.
Let the models reveal information and inconsistencies, or more positively, prove you right. Above all, allow time for practice. Trial and error can be excellent teachers.
Eclipse Process Framework (EPF)
The Eclipse Process Framework (EPF) is an open source project that is managed by the Eclipse Foundation. It lies under the top-level Eclipse Technology Project. It has two goals: To provide an extensible framework and exemplary tools for software
process engineering, method and process authoring, library management, configuring and publishing a process. To provide exemplary and extensible process content for a range of software development and management processes supporting iterative,
agile, and incremental development, and applicable to a broad set of development platforms and applications. For instance, EPF provides the OpenUP/Basic, an agile software development process optimized for small projects.