I typically wear between an 8 and 9 depending on the shoe..I went with an 8.5 and they were perfect!  They mold to your foot and are very comfortable and light weight.  A lot of new flats can give you blisters, but not these.  The fabric is on the thinner side, and I'm hard on my shoes, so I can tell that the toes may not last too long, but other than that, they are awesome!