As an audit intern at Deloitte & Touche, LLP, the skills that benefit you would include: being personable, professional, interested in learning, and willing to help. A big characteristic that's beneficial to audit interns is always asking upper level members of the team if there is anything else they might be able to help out with, especially after completing a previous task.
Of course to be an audit intern you need to know how accounting works in general, but beyond that it really is on the job training. I would say excel and word are used heavily, so it would be best to be familiar with how the programs work. Other than that, I would just focus on your people skills and learning how to work with others; all audits typically consist of teams so you will be constantly working in a group setting.