Wearing the right outfit does make a difference. It is also all in the eye of the hiring officials. I remember hearing about a guy who came in to interview and was turned down because his shirt had a wrinkle in it. While another hiring official in the same company loved his personality and everything and hired him.
Know the Dress Code
As you prepare for the interview, be sure to do some research on the company. Try to find out what the acceptable dress code is. The rule most people follow is to go with what most people wear to work or a step higher. It is possible to overdress for an interview. Be sure your patterns and colors do not clash and are not obnoxiously loud either. Make sure you do not wear a cap or hat to your interview.
Professional/Office Positions
In Professional positions and office work, generally the expectation is be dressed up. For females this would be a nice dress or pants suit. For males it would be a minimum of a button up with slacks, but could be a tie or a suit also. In the financial world, it is generally perceived to be a suit, however if the employees are in button ups or polos, don’t wear a suit or tie.
Warehouse, Fast Food, Etc.
In these roles you typically do not wear shorts. Unlike in professional work, jeans are acceptable in most instances. Preferably wear a polo shirt, but if you wear a t-shirt make sure that it is plain, no distracting images, slogans, etc. Again, knowing your audience is important to how you present yourself. Each company and even each hiring official could have their own preferences, but you should look to see at how others are dressed even if it is only seeing pictures on the company’s website.