Chicago's own Tony Burroughs has a nice post at AC360. Much of it pertains to the stringent methodological requirements of doing African-American genealogy successfully, and one part should be required reading for all genealogists:
Many are unaware of the vast amount of records that exist, and the scarcity of those that are digitized or even catalogued. One institution alone, the National Archives, has only 125,000 scanned images on their website out of 4 billion documents in their collection. That’s one page for every 34,000 documents.Very crudely put, your odds of finding what you're looking for on the internet alone: 33,999 to 1.