At my first job I wore a suit to the interview, and on my first day of work. My manager then came in and told me that nobody wears suits, and I could go with a dress shirt and dress pants. After that I stuck with the attire he suggested, but it was crucial to make sure I did not show up looking like a slob on my first day.
If the attire for your interview, or your job, are not specified, I always suggest that you err on the side of caution. It’s definitely better to be overdressed than underdressed. I’d recommend that you wear your best suit and make sure everything is clean and pressed. Your first impression is crucial to how the interviewer remembers you, and how those around the office will view you. If you overdress they’ll do as my boss did and tell you to dress down the next day, and nothing will be lost. If however you dress too informally, you will be viewed as lazy, or not caring about the job. Don’t be that guy that wears a polo when you should’ve worn a suit. Just don’t do it.