Being the shoe fanatic I am, one of the first things I wanted know was what was my feminine shoe size. The basic rule of thumb in the US and Canadian markets is that you add two to your old male shoe size to get the equivalent femme shoe size.
Therefore, if you wore a size 8 in a men's shoe, your equivalent women's shoe size is a 10.
However, while most people have consistent sizes across types of shoes, sometimes depending on the style of shoe and where it's manufactured, you may have to get one that's larger. I noted that I had to go a size larger for shoes made in Brazil, for example, while others were fairly true to my actual shoe size.
So word to the wise is try them on first before you buy them to make sure they're comfortable and they fit.