I have a specific question and a general question.

Specifiically, I'd like to invest in a nice pair of shoes. I own a single black suit, a single black sport coat and a couple pairs of charcoal, dressy-ish slacks. I have two pairs of black dress shoes I don't particularly like. I do have a decent selection of nice shirts. I'd like to purchase some decent brown oxfords, but I'm guessing, given the rest of my wardrobe, they wouldn't well. For the sake of versatility...to expand the function if this small wardrobe with the least amount of items...what would be the one or two smart purchases to make? Blue/grey sport coat? Brown oxfords?

More generally, what are the staples? Before you become alarmed, I'm 33 and work in "the music industry", so the number of occasions per year that require this sort of attire can probably be counted on two hands, but they are becoming more frequent. For a dilettante such as myself, please help me take the appropriate steps towards a proper wardrobe; a proper wardrobe smaller than my girlfriends.