In general, if you're going to wear a scarf with a dress, especially your favorite LBD, make sure to get a long scarf, longer than average. The purpose of a scarf with a dress is to add flow and mystery—you can't do that with an ordinary scarf. And this scarf should probably be of silk, preferably a heavier weight silk, which looks costly. It doesn't have to be expensive: you can buy a couple of yards of silk at a second hand store and cut it into a dress, or check out the fabric stores specializing in Asian imported fabrics for gorgeous silks at good prices. You don't have to buy one ready-made: spend a couple of hours of TV-watching time hemming it by hand, and you're done.
A little black dress can be dressed up with a silk scarf worn around the head like a movie star. Put the scarf around your neck with two-thirds of its length on one side, then use that long side to come up and cover your hair, wrapping the scarf around your neck to keep it in place. This is especially nice with a dress that has some décolletage: the juxtaposition of deep cleavage and a scarf at the neck is playful in the Italian style.
A white silk scarf looks especially nice if you put it on backwards, so the ends trail over your shoulders, with the body of the scarf around the front of your neck. You might want a brooch to keep it in place, or a pair of matched pins—one for each side. This is also nice for keeping the sun off the sensitive skin of your neck: good for outdoor weddings. For evenings, consider dark gray or black silk. Of course, you can wear colored scarves! But choose the occasion carefully. A trip to the museum on a rainy Saturday might require a scarf of watery blues and greens (but watch out, sometimes cheaper silks run in the rain). To see an ex-lover (and convince him you're much happier without him) wear red, or maybe a print with tiny flowers. Spray it with cologne, to remind him of what he's missing.
