The wardrobe department isn't a bunch of elves there to serve you; they're artists with vision. Honor them.
My mom is an avid musical theatergoer. My dad would always get a subscription to the Syracuse Stage. I was always exposed to theater. So I went to a theater conservatory at Boston University.
My rule of thumb is to always do what's on the page first. Then you can talk to your director about playing with it. Improv frees me up in a character, but I would be mortified if the writers who agonized over their words assumed I thought my improv was more valuable.
