An A-line skirt is one that starts at the waist, as they all do and flares straight down into an A-line, ie, the lines of the skirt flare out consistently on the way down, but not so much that you look like a fairy princess, and not so little that you're hobbled by the skirt. You should avoid tight or fitting skirts designed to accentuate the butt and thighs, very few women can really pull these off successfully, and though you should feel free to wear such a garment in your free time for a touch of glamour, highlighting your ass isn't exactly what you want most of the time.

A nice, straight, long a line skirt that comes down no more or less than a couple of inches off the floor. Not so long that you will trip over it. Not so short that you will be exposing a great deal of ankle. I don't know why, but ankles seem to look awkward under long skirts, almost as if you belong to some sort of cult.