If unsure, ask yourself if you can change the order of the adjectives without changing the meaning of the sentence. If so, they are coordinate, and should have commas between them.
Example № 1: The orchestra played a slow, beautiful, familiar tune.
Note that if one augmented the statement, like so: The orchestra played
a slow, beautiful, vaguely familiar tune -- "vaguely" is describing
(modifying) "familiar," so those two words stay together, undivided by a
Example № 2, one of the best insults ever written: "What kind of spindly, ricket-ridden, milky, wizened, dim-eyed, gammy-handed, limpy line of things will you beget?" (The Lion in Winter, 1968 -- delivered by Katharine Hepburn as Queen Eleanor of Aquitaine to Peter O'Toole's King Henry II.)
Each of those delightfully biting adjectives equally describe "line of things," and the order is relatively unimportant (when rattling it off as a quote, we rarely get them in their actual order, nor the same arrangement twice). According to the test, commas go in between.