1) To be a good night auditor, you probably need to have a reasonable amount of previous F/office - guest agent experience. You really need to understand f/office well so that you can not only provide good service overnight to guests, but be really familiar with the systems of F/office. The night auditor role is to basically check over all the days transactions and correct errors made by the day staff who are often very busy. If you understand well how the computer system works and f/office systems work, you will be much more able to see and correct errors. You also will be able to help management see any other problems that may be arising etc (ie reservation issues, travel agent payments and vouchers, special deals not being honoured, all kinds of smaller things that the hotel may be missing in the chaos of the day?
2) You need to be able to cope with the hours. This is the hardest part of the job. It can mess you about sometimes, and you may sometimes feel exhaustion or depression due to a jetlag like effect. This often comes from not being able to sleep deeply in the day (especially in summer), or waking up after only a few hours sleep and not being able to return to sleep. Normally though you get used to it after time, but it can mess with your moods a little.
3). A logical and annalytical mind.... Often as you work alone, or even if with others, all the staff who's work you are correcting or checking have left and are asleep, so you will have to deduce what went on a lot. You need to be able to make guesses as to where the error may have occured, and know where you can find the information to verify if you were right.