When evaluating fabric quality, focus on Yarn Count (e.g., 40s, 50s, 80s, or 100/2); higher counts generally indicate a finer, softer, and more luxurious feel. Pay close attention to Fabric Weight (GSM - Grams per Square Meter), where 100-130 GSM is standard for dress shirts. Additionally, verify the Weave Type (such as Poplin, Twill, Oxford, or Dobby) as it dictates the fabric's breathability, durability, and formal level. For performance shirts, ensure a Spandex/Elastane content of 3-5% for stretchability.