Closed toe shoes with 3-4 inches heels are considered to be the perfect shoes for the working ladies. However if you cannot manage heels you should go for flats. Another important thing is that your shoes should be clean and should match with your outfit.
On a careful note, flip-flops, sandals, open-toed shoes, extremely high heels, sneakers, and embellished shoes; are referred to informal footwear and should be avoided when going on job or job interview.