Effective interview dress is a combination of what makes you comfortable, what expresses how you feel about yourself and (perhaps) your cultural and ethnic background, and what is appropriate to the field or industry in which you are seeking employment.
Everyone knows what “comfortable” means, but just be aware that what is comfortable at home—say jeans and a T-shirt—will make you very uncomfortable at an interview for an investment banking position. Remember that comfort has physical, emotional, and cultural dimensions. Consider all three in choosing your interview wardrobe.
And what about “expressing how you feel about yourself”? This is fine, dandy, and wholly positive—as long as what you feel about yourself is appropriate to ...