I dont know if this will help anyone but I have read another guide on ebay that is not really clear.
To put it in perspective I am a size 10 australian in clothing (sometimes a 12 depending on the cut)... I shop regularly on Victorias Secret and I tend to buy a size 8M - the strange thing is I fit into a 12 australian in jeans but I fit in size 9 american jeans. (But jeans I find are always dubious in their cut and stuff)
Shoes are same size.... again I have bought many pairs of shoes off Vic Secret... I am a size 7.5 australian or i think that is a 38 - and I have bought from New York, Hawaii and the american websites like Vic Secret or Delias a size 38 - 7.5 (I think 38 is a 7) b/c of the different brands you can buy it depends on the sizing!!!
Do not use Delias as a clothing size guide as the products are made for early teens!
So I am on average or majority of the time an Australian 10 - but I buy an american 8M (if it is a simple cut) like jackets that can be adjusted by a sewing maching...
Hope this helps!!