The primary rule is to "start with what you know." This is not an exercise in the obvious but rather once we take inventory of what we have on hand we can better see where the gaps reside.
As we work our way through a particular conundrum we should also keep mindful of the broader picture. Becoming focused on a single individual, event, or even a given document may blind us to the other resources and evidence.
As a case in point, I have been seeking the parentage of a Czech immigrant to Texas in the 1870s. In addition to untilizing convenient online resources, I racked up a lot of miles visiting local libraries, ethnic resources and county courthouses . The result was quite a pile of census entries, marriage licenses, cemetery listings and county tax returns. Nothing provided that clue I needed to pinpoint his parents or their old country home.
I had performed due diligence in my efforts. I worked from what I had known and stepped backward from his death certificate, to his census entries and on to his tax returns, draft registration and marriage license. Where was the gap?
Thinking through the standard document source list from Genealogy 101, I realized I had never sought out his obituary. -palm slap-
While not providing all of the answers I sought, it did isolate the correct identity of a known brother as well as provide the name of a previously unknown sister. A bit of deeper research on this cluster of family members and I will be close to completing the puzzle.
In some cases, the genealogical brickwall may only be imaginary and can be overcome by going back to the basics and taking a fresh look.