Every piece of information you find (an email, phone, relative, middle initial, address) is a lead that you can further search in Google and in people-finding databases.
Public Records.
Records that the government is required by law to keep and include birth certificates, deeds and professional licenses.
Publicly Accessible Information.
Information generated by a person or entity that can be accessed using commercial databases like LexisNexis, Accurint or Pipl.