I love silk scarves (35 inch squares, as in Hermes carres) but it IS hard to wear them without looking matronly. First, watch the movie The Queen, and make sure you never tie them the way she does! The big no-no is the "old lady" tie where the scarf is folded diagonally and knotted on one shoulder. Ties I like are scarf folded diagonally to a 2" width and then knotted in front mid-chest. Also, fold like that to wrap around your neck and knot in front, back or side as a choker. Fold diagonally with point in front and bring ends around to knot in front over or under, then put necklaces over that. You can always buy a Hermes "how to tie" booklet on ebay. If you really get into it, there is a wonderful Hermes Yahoo group (which also will help on IDing the many crummy fakes).
Oblongs are easy to wear and tend not to have the matronly trouble. Just fling them around. Hermes does not make oblongs though.
As for colors, best are pinks/reds/peaches that flatter you--like makeup that you tie on. Accent colors can pick up your jacket colors. Make sure you love the pattern. All the colors in the pattern don't have to be your favorites, but the field (background color) must be flattering to you.
Resale shops are a great source for silk scarves, and go to the Hermes Yahoo group for instructions on how to handwash them.