First, according to the coat/hair/fur pattern/colour. Put your file in one of these subcategories. ONLY if you can't find an appropriate category, put it in this category (Category:Felis silvestris catus).
Use these categories for predominantly one-coloured cats ("solid" or "self"):
Second, according to breed. If your cat is a purebred, put it in the appropriate subcategory of Category:Cat breeds. If it is no identifiable breed, it can be put in Category:Domestic cats, but this is optional.
Third, according to hair length. If your cat has long hair, put it in Category:Long-haired cats. Medium length and short-haired cats are the most common, so they don't have separate categories. If your cat is hairless, it probably belongs in Category:Sphynx (cat) (a hairless breed).
Fifth, what does the photograph show of your cat? Is it a photograph of the cat's face? Then put it in Category:Cat portraits. Does it show some distinct body part of the cat? Then put it in Category:Cat anatomy. Does it show the cat doing something interesting or unusual, something other than just sitting there? Then put it in Category:Cat behavior.
Sixth, what does the photograph show besides the cat? Is it a photograph of a cat in snow or autumn leaves? Does it show the cat on a fence, in a tree, or on a wall? Then put it in Category:Cats by setting.
Anytime you don't know how to categorise your photo, just put it in this category directly, and someone else will subcategorise it for you.
This category has the following 38 subcategories, out of 38 total.