If you're looking for work, you're looking for compensation. You should never start the conversation or jump into salary without first establishing rapport. However, salary is important and you should know exactly what you want understanding your bottom line before going to an interview.
Just like a job provides a salary range, be prepared with your income range. When analyzing your compensation needs think of a stoplight. Red (Stop) = I can't live on that Yellow (Caution)= If careful, I can get by on that Green (GO) = I can take off with that! Knowing what you need to make will allow you to know when an opportunity is right or when you need to continue your search.
How do I approach the money question? Typically the Recruiter or Hiring Manager will ask you for your compensation needs. If they don't ask and its time for you to inquire, always ask them for their range. Being that you're clear on your salary requirements, knowing their range will allow you to gauge where both parties are and make for a more effective conversation.