Dress for success. When you go for an interview, the rule of thumb is to dress one step above the position you want. If you are going after a job in the service industry, dress the way you expect your supervisor would. If you are looking at an entry-level administrative position, dress as a manager does. No matter what the nature of the job is, your clothes must be clean, pressed, and free of imperfections like dog hair and stains. Your shoes should be neat and in good repair, and can reflect the type of work that you do. They should also be polished.
If you work in the trades, or are interviewing for a job that will lead to wearing a uniform, do not wear your work clothes to your interview. A nice pair of slacks, a shirt with a collar, and a good pair of shoes will put you in a professional and presentable light, and make you look like someone who wants to be taken seriously.
