When selecting knitting yarns, you must prioritize Fiber Composition (e.g., 100% Merino wool, acrylic blends, or recycled polyester) as it dictates the end-product's hand-feel and durability. Pay close attention to Yarn Count (Nm/Ne) and Ply, which determine the thickness and strength. For industrial knitting, ensure the Twist Direction (S or Z twist) and Twist Multiplier are compatible with your machinery to prevent spirality in the finished fabric. Additionally, verify the Moisture Regain percentage to ensure you are paying for fiber, not excess water weight.