I made my cutie mark out of felt and sewed it to my sweater/cardigan on the ... left (?) side of my stomach. The Fluttershy in our group made hers out of felt and put them on pins and made them pseudo brooches that she pinned to the lower part of her skirt, and her girlfriend was Rainbow Dash who sewed hers to the left butt pocket of her denim shorts.
And we all had cutiemark necklaces. I did have earrings, but one of them fell off and got lost forever. :C
As for tails, we kind of... forwent tails and stuck to ears/horn/wings.