Listen to Barbara Poole, career coach, speak on how to dress for a job interview today
When you're dressing for a job interview, whether you're male or female or regardless of age, I think the rule of thumb is just to dress in a professional and neat manner. And in general it is better to be overdressed than underdressed. The job candidate who arrives in a smart outfit will always make a great first impression whatever the work environment.
If you are in doubt about whether you're dressing for the interview will match the culture of the company you're interviewing with, I think it is always a good idea to try to do your homework ahead of time. You can do this in several ways. You can research the company by talking to people you may know who work on the inside or by simply going out to the Internet and finding out what you can about the company.
Another easy way to find out is to call the Human Resources Department. They are usually quite helpful in answering your questions and there is no shame in paying a call to the Human Resources Director and saying, "I have an interview on Tuesday for XYZ position and I'm wondering if you could tell me what the appropriate interview dress would be." They will usually be quite direct with you.