When we use more than one adjective before a noun, we usually follow a certain order to arrange them in a way that it forms a grammatically correct sentence. That order is called the Order of Adjectives.
The general order that we follow is: Determiner/Opinion Adjectives/Fact Adjectives/Nouns. This implies that we should place determiners like articles (a,an, the), possessives (my, your, etc.), demonstratives (this, that, etc.), quantifiers (some, any, few, many, etc.) and numbers (one, two, three, etc.) the first in the order. Opinions should come before facts, and finally the noun should come. Fact adjectives can be further broken down and arranged in the following order: other / size, shape, age, colour / origin / material / purpose.
Therefore, in the above sentence, ‘some good brown Italian leather riding boots’ is arranged in the correct order. This is so because Determiners like quantifiers (some) come the first in order before anything; opinions (good)come after Determiners; information like colour (brown) comes after the opinion; origin (Italian) comes after the colour; material (leather) comes after the origin and finally the purpose (riding) comes just before the main noun (boots).
Some examples: a gorgeous pink Armani hand purse, my fabulous new red sports car, etc.