• understand the problem - as given/stated by the problen owner
• understand the problem context and its constraints
• validate the problem with what the problem owner wants to achieve - not always the same as the problem
• develop one or more candidate solutions
• assess the solutions against the problem and its constraints
• revisit the problem and determine if, by varing the problem, a more optimum solution is possible
• agree the problem and solution with the problem owner
• document everything
• based upon the solution, develop a set of requirements that defines the details of the solution
• make sure the PM implements the solution you have defined, not what they think should be implemented.
  

Notice:

• the solution defines project requirements, not the other way round.
• the combination of problem/solution is optimised, not just the solution.
• these rules apply to a range of problem types, not just Information Technology.
• don't confuse a reduction in cost with an increase in efficiency.
  

Bernard Robertson-Dunn, 22 June 2010