Usually, I hesitate to say that art writing has rules, but there are some glaring mistakes that should be avoided or else your writing will, at the very least, lack conceptual heft and make you seem unaccustomed to writing about the world of images.
Rule #1: Never say “piece of art”
With rare exceptions, when referring to an artwork, do not say or write “piece” or “piece of art.” A piece, by definition, implies part of a whole. As such, you are stating that this singular work is incomplete. Saying piece becomes particularly troubling when used in reference to an artist in a group exhibition when he or she shows only one artwork.
So, how did we become accustomed to discussing artworks in terms of pieces? My assumption is an etymological one: pièce is also used in the French language to refer to art. Possibly more relevant to a discussion of partial artworks is one of the Vasari-type leftovers that breaks through to the present day, that is, an artist’s output consists of a series of developments that adds up to their entire output, their oeuvre. With this notion, one must see individual artworks as pieces that add up to a complete body of work made throughout an artist’s life.