I keep a small wallet with all I need - we really don't' need half our belongings with us everywhere we go, girls!
I keep it safe in a snapped pocket - some shirts/jackets with inside pockets.
This also keep me from laying my 'purse' down where it can get snatched or forgotten...
I thought the main reason was for make-up and feminine hygiene products-- not the obvious like to contain money and credit cards.