When evaluating cotton fabric, you must prioritize Yarn Count (e.g., 30s, 40s, 60s) and GSM (Grams per Square Meter). A higher yarn count typically indicates a finer, smoother fabric suitable for high-end shirts, while GSM determines the weight and opacity. For garment production, ensure the Shrinkage Rate is controlled within ±3% to prevent sizing issues after washing. Additionally, verify the Color Fastness rating (Grade 4 or above) to ensure the textile maintains its appearance after repeated laundering.