Gather as much information as possible about the signature in question. Identify the type of artifact in possession, the materials used, the subject matter, and the history of the artifact. Details about previous owners may be useful. If previous owners are still living and agree to be contacted about the artifact, more specific information about the artist or the location of the artwork and when it was created may be obtained. Information about the artifact narrows the search field for where an artist may have been working and what period of time he or she worked.
Consult a collector's guide, preferably one that focuses on the type of medium: painting, wrought iron, brass, poster, illustration or sculpture. Make a list of artists whose work is similar to the artifact or that was constructed in the same location as the artifact.
Register with an online database of artist's signatures. Search the names of the artists whose work resembles the type of artifact in possession or was who working in the same location as the artifact was constructed. Compare signatures until one or more close matches are found.
If the signature does not match or closely resemble any of the signatures in the database, repeat the process with additional collector's guides and keep a record of artists whose signatures do not match.