Men
One of the ideal ways to dress could be a navy or black suit or a sport coat with a tie and a long-sleeved light colored shirt. Be sure to wear a belt that matches your shoes. For some, this may not be possible. If so, then you should ensure that you sport a white shirt with dark trousers. Formal shoes are the best bet; stay away from boots or sneakers.
Make sure your hair and nails are clean and trimmed. Unless you are applying for a creative post, do not sport hands full of rings or bracelets and other such charms.
Women
You can wear a classic skirt suit with a light colored shirt or a simple dress that does not rise above the knee. Do not wear anything too tight or revealing. Be sure to use coordinated accessories in muted tones.
Ensure your hair is well ordered and in place. Try to avoid sporting shocking colors on your nails and hair. The same applies to your make up which should be natural, as much as possible.
If you do not have the appropriate wardrobe, consider borrowing them for the purpose of the interview. If needed, consider borrowing clothes and accessories from friends and family. No matter what you get, the right clothes will help you get the job you want.