Belts for any reason other than holding my trousers up - I have never had a neat, trim waist, so it's not an area I want to draw attention to.
Stiletto heels - I have a hip condition that means I just can't wear them. I do block heels or wedges though, but it's a nightmare when they're not in fashion and there's only spindly heels if I don't want flats. At the other end of the scale, sliders and flipflops are out for same reason.