There is a Royal Order of Adjectives, and you follow it without knowing what it is

There is a Royal Order of Adjectives, and you follow it without knowing what it is—a particular sequence to use when more than one adjective precedes a noun. There are exceptions, of course, because English is three languages in a trenchcoat. According to the Cambridge Dictionary, in general, the proper order is:

Opinion
Size
Physical quality
Shape
Age
Color
Origin
Material
Type
Purpose

Most people couldn't tell you this rule, but everyone follows it. If you use the wrong order, it just sounds weird. If you have a fancy new blue metal lunchbox but call it a metal new fancy blue lunchbox, people might be worried you are having a stroke. 

Adjectival Order: Why A "Big Red Balloon", not a "Red Big Balloon"?

This list has several slight variations. Quills and Quotes, which adds number and nationality, suggests using "Never OPEN My Purse" to remember "number, opinion, physical condition, essentials (size, shape, age, color), nationality, material, and purpose." The delightfully named  Mrs. Lorber's 4th grade Website proposes ANOSASCOMP for "article, number, opinion, size, age, shape, color, origin, material and purpose." These mnemonics seem like a stretch, but your mileage may vary. 

If you are wondering how to use commas with adjectives, there is a rule about that, too.