For ladies who prefer 'power dressing' for corporate interviews the trick is to choose a professional suit or blouse and skirt, not a dress that you would wear out to a cocktail bar; anything too flimsy or revealing looks desperate rather than professional and is unlikely to impress. Similarly, don't overdo the jewellery, weighing yourself down with massive earrings or tons of bracelets does not give the impression that you are ready for a practical day's work at the office.
For both men and women seeking a professional appearance, go for a sensible suit in black, navy blue or grey. For women, ensure that the suit skirt is not too tight or short, whilst men should always pick a sensible tie to wear, nothing from the novelty tie rack. As for other aspects of general appearance, common mistakes include too much aftershave and deodorant for men or too much perfume and make up for women; a little of each is absolutely fine and positively encouraged, but don't overdo it as an overpowering scent could leave the interviewer with a skewed perception of you. Shoes should be smart and sensible and well polished if required, similarly nails should be neatly trimmed. If possible, carry a briefcase or portfolio folder, try to avoid tatty bags and casual handbags or man-bags.