Macromedia has a sample chapter for download from a book called ‘Using ActionScript in Flash’. The chapter is ‘Using Best Practices‘ and has some good tips and suggestions.
“Best practices are particularly useful when you share FLA files with other Flash developers, or you want to create consistent and readable ActionScript. Adopting best practices can help you increase productivity and improve your workflow whether you’re working solo or on a team. The “Using Best Practices” chapter covers recommended practices and naming conventions in Flash development, as well as best practices for writing ActionScript 2.0.”