First thing to find is a square scarf. I found mine for $0.25 at a thrift store (definitely beats some scarves I've seen for $25.00+).
I folded it with right sides in and pin down the sides to sew.
Turned it right side out and it was ready to wear!
Seriously, one of the simplest things ever with a satisfactory result. For more details, head on over to Belrossa!