Ans: This is key for both comfort and style. A good denim shirt should fit comfortably on your shoulders without bunching, and the sleeves should reach at your wrists or mid-lower arm depending upon the look you're going for. The middle should be fitted without being too tight, considering some layering whenever needed.

Body Type: Look for a fit that compliments your body. Classic fits work well mostly, while slim fits can emphasize a lean form and relaxed up fits offer a more casual look.
Length: Choose if you prefer your shirt to hit at the hip, or have a longer, more casual drape.
Comfort: The shirt shouldn't be excessively close or restrict movement. Try it on and move around to ensure a comfortable fit.
Collars: Stiff collars offer a more formal look, while floppy collars with buttons are more casual.
Pockets: Chest pockets are classic, but a few shirts have no pockets for a cleaner look.