Colette says that an ill-fitting outfit is the fast way to look unprofessional: "Never, ever, compromise on fit. The quickest way to diminish the perception of professionalism is through an ill-filling outfit."
While it mind sound obvious, women tend to buy a size up, rather than the garment that actually fits. "We’ve found that most women dress a size or two too big for their frame . . . Make sure fit across the shoulders is spot on (on the shoulder, not off the shoulder) and sleeve length is to the wrist (not the top of thumb)," Colette suggests.