The rule is generally as follows;
1. The first adjective in the sequence, and the one which is placed furthest from the noun is generally the most subjective one. This is usually an opinion, such as beautiful or funny.
2. If there are three adjectives (which is usually the maximum), other descriptive features, such as colour, often come in the middle position.
3.The most essential and undeniable feature of the noun usually goes immediately before it, and is the final adjective in the sequence. In the case of an object, it might be the material it's made of, or in the case of a person it might be their nationality.
NB There are sometimes exceptions, for example 'A tall, handsome man' or 'a long, boring book', but in general these are useful rules to follow.
Here's a little exercise for you, Robin. Put the adjectives in the right order.
1. That's a ............ briefcase. (leather, useful, little)
2. His girlfriend is a ................ woman (clever, Japanese, young)
3. They live in a/an ................... cottage. (country, old, charming)