I live by blot powder! its amazing the shade you use really doesnt matter because its sheer...But i usualy buy meduim or meduim dark, I wear NC45 and NW 45
I ONLY use blot powder. used over a very light foundation its a great day look especially in hot weather. just bring a compact and add on as you go. I use Dark, and i don't really know my mac foundation colour, but i wear the NC30 concealer when i lose my tan so.. prolly a shade or two darker normally.
this product isnt really that hard to match imo. i use medium-dark nartural msf and the MA told me i could use dark or medium-dark. I didnt see any difference in them and went with what the MA suggested which was dark. i cant wait till the summer to see how much of a punch this baby packs against my oily skin. *crosses fingers*