What equipment Serbs used in medieval period depends on the period itself, in general it was an overall mix of Eastern Roman, German and Italian, same counts for clothing.
But then again, depends on the period and don't forget the German, Italan, Catalan, Aragones, Spaniard, Ossetian ,Cuman, Anatolian Turk, Tatar, Hungarian, Wallachian, Bohemian, Frank, French, Swiss and whole bunch of other mercenaries mentioned in different sources, so we can't generalize things.