When sourcing 100% cotton fabric, you must prioritize Yarn Count (e.g., 40s, 60s, 80s) and Thread Count (TC), as these directly determine the fabric's fineness and durability. Higher yarn counts indicate a finer thread, resulting in a softer hand-feel. Additionally, verify the GSM (Grams per Square Meter) to ensure the weight matches your specific application, whether it be lightweight shirting or heavy-duty canvas. Always request Colorfastness test reports (Grade 4 or higher) and Shrinkage rate data (ideally <3%) to ensure the finished garment maintains its shape and color after washing.