@GreenSkyOverMe @ayis
*mostly* it's a question of whether you're emphasizing a trait or distinguishing between several things, and i think that's even kinda true on some that change the meaning
"mi amigo viejo" tells you which one…the old one, not the young one
"mi viejo amigo" is emphasizing the age of the friendship
also, poetry can be a little loosey goosey with it