A tie bar should be worn between the third and fourth buttons. Tie bars should also be clipped to the placket of the shirt and not just to the front and back ends of the tie itself.
Before attaching a tie bar, the tie should be pulled upward just a bit so that the wearer doesn't feel that he can't move comfortably. Doing so also adds a subtle visual allure to the outfit. It's recommended that a tie bar not be wider than the tie itself and that it not be worn with a waistcoat or a cardigan, mainly because both clothing items already keep the tie in place. Generally, the width of a tie bar should be between 1 inch and 3/4 inch.
Silver is the most recommended color for tie bars because it goes with everything and is a classic color. Gold is also a viable option as long as the wearer has gold accessories. All metals worn with an outfit should be the same color.
Tie bars are available in a side clasp style and a pinch clasp style. A slide clasp may be preferable with a thin tie, while a pinch clap is usually better suited for thicker tie fabrics.