As a professional genealogist, I read, scan, and look at many books, newspapers, journals, websites, etc.
As soon as I think that a particular book, etc., may be a source for information on the ancestor which I am searching, I do an important thing – I write down my citation for the source. It makes no difference as to if the source will be used to prove or disprove a bit of information – I will write down the citation and add it to my “Sources” listing.
There are a variety of books and websites of proper citations. The one that is recommended for those researching families is Evidence Explained, Citing History Sources from Artifacts to Cyberspace, by Elizabeth Shown Mills. The First Edition was copyrighted in 2007, and the Second in 2009. Ms. Mills begins her book by explaining the fundamentals of evidence analysis. Then, in the following 778 pages, she covers the fundamentals of citations, including electronic sources.
As a genealogist, I would be lost without this book. It is surely the most used book that I own. One can order a copy of the book from several sources. Google it! And, one can also order various QuickSheets that pack easier in a research bag!