Summer is dying, and fall is on the way, whatever the temp. In a nod to back-to-school nostalgia, wear a backpack instead of a purse. While it's still blazing, wear the most beautifully patterned cotton frocks possible, in apple yellow, late leaf green, ripest black plum, sky-blue. Put your hair up in alarmingly elaborate and sloppy do's, like when you were first allowed to brush it yourself.