The buckle is an important factor. Some buckles are made of pure gold, which can show that the owner is elegant and gentle. The copper buckles show the man's masculine temperament. The large buckles show man's fortitude and the oval buckles show the man's maturity. Also, the square buckles means that a man is successful.
For the man, the width of the belt is supposed to be about 3.5 cm if you are on a formal occasion. Too narrow, it can show a man's masculine temperament. Too wide, it gives others a casual feeling which means that you are not paying attention on the occasion. Not only the width of a belt should be noticed, but also the length. A great and appropriate belt's length should be that when you wear it, the tail should be between the second and the third pant loop. Besides, the design of the belt is important too. On the formal occasion, the belt should be clear. Don't have too much decoration. The pure the belt is, the better the effect will be.
When matching the suit, the belt's color is supposed to be the same as the leather shoes. Both of them are necessary for successful man. In my opinion, the black is the best in terms of the color. Of course, on a casual occasion, the canvas belt also is a not bad choice. All of these is my experience. I hope it can do someone a favor.