Square, oblong, small and large scarves can be worn with a suit coat. Because a suit coat is a more formal piece, consider wearing a silk scarf or silk-blend scarf. Whether you tie it snuggly around your neck or keep it loosely hung under the coat's collar, a scarf is an easy way to add color and texture to your look, as well as jazz up an old suit coat.
Tie a small square scarf snugly around you neck, keeping the knot just off to the left or right side of your neck. Depending on the size of your neck and suit coat, the ends of the scarf may stick out past the collar.
Wear a square scarf as an ascot. Lay it flat and upside-down, with a corner facing you so that it looks like a diamond. Fold the bottom and top ends of the diamond to the scarf's center. Place the middle of the scarf around the back of your neck and flip one end over the other. Do not make a knot. Instead, leave the ends out or tuck them into your blouse or suit coat.
Drape an oblong scarf around your neck tucked under the collar of the suit coat so that the ends fall evenly on either side. The collar will help hold the scarf in place.
Fold an oblong scarf in half so that it is half its original length. Holding the folded end in one hand and the two free ends in the other hand, place it around the back of your neck so that the folded end falls on one side and the free ends fall on the other side. Then take the free ends and stick them through the loop created by the fold. You can pull it tight around your neck and stick the free ends in your buttoned suit coat, or keep the "knot" low on your chest and secure it with a broach or scarf pin.
Lay flat a large square scarf and bring the top and bottom ends to the middle to make an envelope fold. Loop it loosely around the back of your neck; bring one end over the other end, then over again like you would a necktie. Secure a knot and let the scarf rest on your chest. This will work only if you wear the suit coat open.