Country of Origin
Every stamp, with the exception of those issued by Great Britain, will have the name of the country of origin printed on it. This is the first point of identification. Once you've determined which country issued the stamp, find that section in your catalog.
Stamps issued by Great Britain will always, without fail, have a portrait of the reigning monarch included on the face of the stamp. Whatever other artwork is on the stamp, the portrait will be within the framework of that image.
Date
If the stamp has a date printed on it, you can locate the listing of stamps issued in that year within the particular country's section in the catalog. If no year is exhibited on the stamp, you need to look at the artwork.
Artwork
The artwork on the stamp may depict a particular event, such as the moon landing. Such a stamp would have been issued in 1969 or later. Apollo 11 landed on the moon and Neil Armstrong stepped onto the moon's surface in 1969. When identifying stamps, always consider the artwork or image depicted. Stamps are often used to commemorate famous events and people.
For example, Prince Charles and Lady Di were married in July of 1981. Numerous stamps were issued depicting this event. If your stamp has Canada as the country of origin and the artwork depicts this famous wedding couple, you would look at the listing of the stamps issued by Canada in 1981 and find within that listing the wedding between Prince Charles and Lady Di. Then look at the description given of stamps within those parameters.
Description
A description includes the size and color of the stamp, its denomination, perforation size and any variations. Though catalogues include many pictures of stamps, no one catalogue can have a picture of every stamp issued. Hence, the need for these detailed descriptions. Use the descriptions to narrow down the identification process.
Catalogue ID
The catalog will provide a specific identification number; the correlation between the stamp and that ID number is unique to the catalog you use. The number that a Scott catalog uses will not be the same as one used for that stamp in a Gibbons catalog. When you store your stamp in a stamp album, include in the identification information the catalog you used and the ID number given that stamp in that catalog.