Just go for a really nice silk black shirt, and dark gray or another dark colour tie (not black though..i know the designer alexander mcqueen makes ties with skull print but its hard to find now) ....plain silver ring band...or something with ancient language enscripted on it...and black pants.and wear the boots you like.you want to look nice for this occasion, so don't overdo the goth thing..I mean like...the "hot topic" goth thing with spikes everywhere and makeup all over your face and eyes.just use subtle things..but yeah just lots of very dark colours will get your point across and some silver rings and maybe plain silver chain necklace...the guy kind haha.oh and do your hair kinda emo if it's not already cut like that?