Hi MKnight Welcome Well if you are asking about how we do categorize articles technically than i have to refer you to How do I add an article to a category If it was not the case than the way i proceed is the following I read the into of the article and find that it is about an Armoured fighting vehicle   I go to that article and check in which category it is contained The answer found is CategoryArmored fighting vehicles But in this category there are other more specified subcategories such as CategoryArmored fighting vehicles by era and CategoryArmored fighting vehicles by nationality I then choose CategoryInterwar armored fighting vehicles and CategoryInterwar armored fighting vehicles as the more appropriate categories for the article