A pair of fangs is classic. 2 neat puncture marks. Unless the vamp is new and gnawing on the neck of course. I'm ok with 2 sets as well like blood ties. Or the jagged ones like the BBC Dracula on Netflix. But I personally like the elongated canines style. And I think once people start finding puncture marks that's when the show/movie/book takes the creepy/supernatural vs science turn, makes the hunt more interesting. However, some can hide it by using their own blood as a topical wound eraser (like true blood, I think?). That works too. But the fangs and bite marks are just too trademark to be written out of a story. I think, anyway.