These kitten ears are just triangles but you can add round ears, long ears whatever. I just decided where I wanted the ears and attached pink yarn at the right-most side of the first ear then crocheted a few rows decreasing as I moved up. I then crocheted around the edge of the ear with black and voila. I added a tulle bow for a little extra something.
Although she didn't have a full costume, my baby girl was a kitty for her very first Halloween because her big brother was a doggie :)