Dark grey suit (*NEVER* black), no pinstripes, no zoot suit. Just a plain dark grey suit. Make sure to have the suit altered to fit you well. Sleeve lengths should be appropriate and shoulders shouldn't be super wide. Flat fronts work best if they fit well, if they don't pleats should be OK.
White shirt that is freshly ironed and make sure the collars have collar stays (plastic is OK, metal is better)
Red or blue tie, nice knot that is centered with the tip down to the top of your belt. Short tie = used car salesman. Long tie = used car salesman.
No cufflinks. You don't have enough scratch (money or experience) to make it work.
Shoes should be captoe oxfords, freshly polished.
Don't wear a Timex. Have a nice looking watch, even if it is a citizen or something like that.
Get a folio for your resumes, don't get one with a calculator, bring your own if you think you need it (bring it anyway). That way you'll look prepped.
This combo has never lost for me. I have received an offer on about 80% of my interviews in the finance world.