A tie is the gentleman's most noticeable accessory, and it is not to be taken lightly. It's hand should be thick, either with a thin batting and thick outer shell, or a thick batting and thin outer shell. For silk ties, rub your hand across it lightly; if it feels rough, it is possibly not a high quality tie.
EDIT: Picture was taken before I learned how to tie a Double Windsor.
Ah, the knot. In my opinion the knot makes or breaks the tie. I always, I repeat always, go for the Full Windsor (also called the Double Windsor). This knot is larger than most others, is perfectly symmetrical, allows for the "dimple" if so desired, and its prominence accentuates both the shirt and the suit-coat. It is not a sloppy knot like the Half-Windsor, small knot, or military knot.