You've heard this all before: Make sure your hair looks nice, take a bath, brush your teeth, clean your fingernails and wear nice clothes. But WHICH nice clothes? There are two types of interview outfits.
If you are interviewing for a position which requires some experience, you'll probably want to wear a suit. Grey or blue are good. Black can seem overpowering. A nice button-down shirt. You can never go wrong with white, but some muted colors are OK. Blue oxford cloth would be a reasonable choice. Sometimes yellow. I don't suggest pink! A nice silk tie to match the suit. Black polished shoes.
For a more entry level position, you can dress more casually. Dress slacks in grey, blue or black. A nice button down shirt, and a tie. You can add a jacket if you like, but it's not necessary. Here is a picture of the various styles of interview dress .
Ties are a topic to themselves. A relatively conservative tie is good for an interview. No Bugs Bunny ties! You can always choose a solid color tie to match your outfit. Another favorite is the "rep" tie. This is the diagonal striped ties. If you must be fancy, a small conservative print might work.