For editions printed in 16th- or 17th-century Germany, VD16 is the first place to look. But for the 15th century, there are two indispensable indices: The Gesamtkatalog der Wiegendrucke and the Incunabula Short Title Catalog. Both are searchable online databases for long-running projects to index all books printed between the invention of printing around 1452/53 and the end of the century. Both databases will provide the same basic information (printer, place and date of publication, format, some additional bibliography and location of known copies), but each offers somewhat different additional information, and sometimes they disagree even about the basics, so it's a good idea to check both.
I find ISTC numbers a bit opaque and unwieldy, but for the time being they offer the most easily citable and searchable index for 15th-century printing. I prefer the system in Goff, as it's easy to remember that "S-308" refers to the 1493 Latin edition of Hartmann Schedel's Liber cronicarum printed by Anton Koberger in Nuremberg, while the ISTC number "is0030800" is much less memorable. The ISTC, however, is not limited to American libraries and is being constantly updated. The GW numbers are also widely used, but the regular numbers end somewhere in the middle of the database. Recently the GW has made its entire record set searchable, but the mixture of regular GW identifers and provisional "m" numbers makes the ISTC my preferred citation for now.
It's good to be familiar with the history and limitations of both projects, about which a number of articles have been written. (A good place to start is "Counting Incunables: The IISTC CD-ROM," Huntington Library Quarterly 61 : 457-529.) But even upon first use both databases will quickly point the user towards key elements of a work's edition history.