There is an art to writing tight objectives. A long standing method is to write SMART objectives:

  • Specific
  • Measurable
  • Achievable
  • Realistic
  • Time bound

You will often need some technical knowledge rather than just project management knowledge to work out if a project is realistic or achievable. For example, you would likely need an engineer to advise you as to whether a bridge building project was achievable within the budget or time frame.

This link has a range of resources about writing SMART objectives.