The left-right proportions of the suit should be equal. Check to be sure that central seams and features are truly centered.
Your suit should not be too baggy. Often on the side of a garment that is too large. Your suit should be fit your waist.
The fit of the suit around the arm holes is determined by cutting of the fabric. The fabric around the armpits should fit your body.
Often the fabric across your shoulders will buckle if the cut is not right. A collar that juts away from your neck
During your fitting you should have the chance to determine the exact placement of the waistline button.
Make sure that your labels have been hand-stitched by looking at the underside for tiny needle marks. Lapel holds and maintains roundness and shape.
At the cuff should be four real button holes. Ready made suits often feature false button holes and do not have this real button holes.
Buttons are the very important part of suit, jacket or shirt. Buttons should be made of real animal horns, not plastic.