When preparing for the CompTIA Security+ (SY0-201) exam, you should understand different social engineering tactics such as dumpster diving.
Dumpster diving is exactly what it sounds like: searching through trash to gain information from discarded documents. Discarded papers can have written notes or important documents. On a personal basis this includes preapproved credit applications or blank checks given by credit card companies.
Documentation with any type of Personally Identifiable Information (PII) should be shredded or burned.
Other social engineering tactics you should know about are:
CompTIA Security+: Get Certified Get Ahead: SY0-201 Study Guide