Welcome to the Cove.
You can look for following during audit:-
1)Master list of documents (such as SOPs, WIs, Formats) are prepared, updated with current rev. no.? Documents as per master list are available?
-Whether the documents that are issued are "really"controlled?
2)Are documents reviewed and approved by authorised persons prior to issue?
Documents issue/changes are reviewed and approved by the same functions that originally performed the review and approval?
3)Obsolete documents are suitably identified and retained as per defined retention time?
4) Documents of external orgin are under document control?
5)Documents(WI) are available at place of work/accessable?
6) Whether documents/records are stored in proper location?
7)Records disposal established and followed?
These are some guidelines. However you have to develope a check list to suit you conditions.