All too often, family historians rely on secondary sources of information such as transcripts and indexes (such as the IGI). They are fine as "finding" tools to locate ancestors, but they are subject to errors and omissions. I would always recommend that after finding "data" in secondary sources, that you always seek out the primary source, (that's the place where the information originally came from), and where possible, obtain a copy of it.

In addition to parish baptism, marriage and burial registers and censuses, there are many other primary resources that family historians rarely look to for information, and many really excellent secondary resources that were published in the 1800s.

Illustrated on the bookshelf:

• Pigot's 1841 Directory, with thousands of names, and descriptions of towns & villages
  
  
• Parish History, written by a vicar in 1898
  
  
• County Guide book, published in 1912
  
  
• County Directory of Durham (huge! and with 1,300 pages) published in 1894
  
  
• Three volumes of Phillimore's Parish Marriage Register Transcripts, published in 1895 covering every marriage in every parish in each county from the start of registers (1538) to 1812. This set for Leicestershire has 12 volumes.