I Cannot Place My Book by These Methods, Now What?
Some publishers do not use any of the above methods to distinguish their books. The older a book is, the more likely it is that it will contain little information to help you place its edition. If you come across a book that has no date and no further information it is time for you to become a researcher. If a date exists, an author's bibliography is the first place to start. If no date is printed, you might need to consult one of multiple reference guides that exist with information and often photographs of early edition books. Another great tool that has erupted recently is, of course, the internet. Often you can discover information about the printing of your book simply by searching the internet for the specific title or the publishing history of that title. Another good way to go about dating a book is to research the publishing company. Various websites and books exist that detail the histories of individual publishing houses. Sometimes you can get very lucky and see a photograph of a copy of your book; other times you might simply come across a list of titles published with dates. Research is often the method by which you can be the most sure about the edition of your book. Even if you are fairly certain you have a first edition, research can often solidify your knowledge.
First Printings
Thus far we have discussed the first edition of books. When we defined "edition" we noted that multiple printings might occur in one edition. This fact allows for an even smaller set of a book's publication to become even more valuable than a mere first edition. The absolutely most valuable copy of a book is a first printing of a first edition. Fret not, second, third, and every printing of a first edition thereafter is highly sought, but the first printing means that the book was never seen in print before that copy. Almost universally, a publisher will note "first printing" along with "first edition." Again, research is your best friend when it comes to making sure you have a first printing.