I guess it depends on who you are trying to scare.
I like to dress nice, would wear a suit and tie every day if my lifestyle accomodated it (see photo
here), but for some reason I usually don't. Black and midnight blue or seafoam green are preferred colors. Two earrings. I like my hair short but rarely have it cut so it's usually shaggy. I'm out of the habit of dyeing it because of work but would bleach my hair if I could. Tattoos are not visible when I am clothed, and I don't walk around naked in public. The only brand name I wear is Sanrio - wallets, pens, stationery.
People only get scared of me when they actually get to know me. I like (of course) horror films, weird music, modern literature, spicy food and lots of alcohol. For some reason that's enough to scare people... but those are the people I don't want to know anyway.