If I were to be staging my own production of Everyman, I would costume the allegorical characters in modern clothing. I would do this because I think it makes most sense in the context of the play, especially since Everyman does not recognize Death at first. Perhaps I would have death wearing some sharp tailored suit, like the devil wore in the film Devil’s Advocate. It would make sense to me that when Death reveals himself to Everyman, he could reveal something that would make more sense to show that he is Death. Perhaps he has souls tucked into his suit jacket (or images of such).
Just by title alone, I think that Everyman would gather more attention if the viewers could relate as they are supposed to, and put themselves into the character of Everyman. So using modern dress would allow them to do so without too much of a stretch of the imagination.
As far as props, I think the wardrobe would explain most of the characters so they probably would not be as necessary in my production. And it would also be the exceptional acting skills by my cast to bring forth the qualities of knowledge, beauty, strength etc. instead of using props to literally show these qualities,
Finally, I would use minimal stage props, and use more lighting effects. For example, use bright white lighting when the angel appears. I think the language of the play, along with proper lighting and great acting will bring forth a new interest in the Everyman play for the modern audience.