A properly fitting waistcoat is crucial for a polished appearance. Here are some fitting guidelines: The waistcoat should fit snugly but not be too tight or restrictive. The bottom of the waistcoat should cover the waistband of your trousers and follow your natural waistline. The armholes should be high and close-fitting, allowing easy movement of the arms. The length should be such that it doesn't bunch up or ride up when you move or sit. The buttons should be able to close without pulling or causing gaps in the fabric. Remember that the fit may vary depending on personal preferences and body type, but these general guidelines will help achieve a stylish and comfortable appearance.