I'm always pleasantly surprised when a woman takes the trouble to dress nicely for a date with me. To think that they have gone to all that trouble is very flattering. A dress with high heels is always nice. It's true to say that the person matters a lot more than what they are wearing, but on a first date at least I think its good to look great. It does matter to me.
This depends on if your boyfriend or friend really truly accepts you as who you are, example maybe your a country girl, if he accepts you as that than it doesn't matter what you look like its who YOU are not your clothes.