I'd likely hit a basic darkened or even red-ish eye makeup or if you don't want to fuss with makeup, dark or mirrored shades with the basic black clothing. I love the idea of wearing a dress shirt with a tie (blood red tie with black shirt and pants? Check out your local thrift stores so you aren't spending lots of $) so you'd look like a very dapper demon. The horns and wings with the classic dressy clothing would be an interesting contrast. I've always liked the idea of a super fashionable, classy looking devil/demon - they don't all have to be covered in filth or ugly.