OMG these are so very very cute... So I wear a 8 1/2 and I got Medium... they fit a little snug but that's like with any new pair of shoes, it's up to you if you want to go bigger.  They have a rubber sole and lots of padding inside... very comfortable.  Also it's not glitter on the outside so you don't have to worry about it coming off throughout the night.  I have been looking for the perfect shoes and these are them...  I love them and they are going to go perfect with my Halloween costume and my outfit for my Twilight weekend!!!!  ENJOY!!!!!!