For a perfectly square table you may be tempted to use four matching pieces for a perfectly symmetrical look. However you can get a more intriguing look by using two pieces or groups one in each corner. Try a tall vase or lantern in one corner with a stack of two or three books in the other (and an airy sculptural accent on top).
Don’t forget when styling a glass coffee table that it’s not just about what goes on top but also what goes below. A see-through table practically demands a graphic rug. Try a black-and-white rug and use similarly stark accents in differing shapes or leave the top completely undressed and let the rug be the star of the show.