You need something structured (as in non-stretch), probably a simple sleeveless but form-fitting shift dress (not a-line but mit skin-tight) with maybe asymmetric detail, in black, with nude pointed courts (not too high, fine do mid heel ones) if you want to play it totally safe. Or a jazzier colour of you are feeling beaver. No open toes (they might be fine but pointed courts are just as fashionable and safer option, plus they will go with a more structured dress better then strappy sandals).