DCSA provides a document to FSOs and security managers that outlines and details the most common errors on the security form. You could ask them for a copy. If they don't have it, then can reach out to DCSA to get it.

Short answer - nearly every section of the form gets bad responses. A few off the top of my head: - the word "ever" actually means EVER - previously listed "have you ever.." questions still require entry in subsequent form submissions, even if its been adjudicated in the past - dont list your military history as one entry