labor partner

Hi all,
In a few weeks I get to be my sisters support person for the second time around. I have four children of my own, and I am a nursing student to top it all. My sister is going to receive an epidural this time. I am excited about being there and want this to also be a learning experience. What I want to know is what is done prior to the epidural, assessments, possible complications, and any other insight would be greatly appreciated. I know the nurses will be busy and won't be able to answer my questions in great depth. I want to be some what knowledgable. thanks you for the help