Here are some great standbys:

• What about this is important to you?
  
• How can I help to make this better for us?
  
• How would you like me to proceed?
  
• What is it that brought us into this situation?
  
• How can we solve this problem?
  
• What’s the objective? / What are we trying to accomplish here?
  
• How am I supposed to do that?
  

–Never split the difference, p.154