When evaluating winter coats, focus on insulation material, waterproof ratings, and breathability. For insulation, check the Fill Power (FP) for down (600+ is premium) or the grams per square meter (gsm) for synthetic fills. Ensure the outer shell has a Durable Water Repellent (DWR) coating and a waterproof rating of at least 5,000mm to 10,000mm for standard winter conditions. Additionally, verify that seam sealing (critically taped or fully taped) is applied to prevent water leakage through stitching.