Selecting the correct fiber blend is critical for the end-product's performance. For activewear, prioritize synthetic blends like Nylon or Polyester with 5-15% Spandex for elasticity and moisture-wicking. For high-end fashion, focus on natural fibers like Silk, Linen, or Organic Cotton which offer superior breathability and skin-friendliness. Always request a detailed composition analysis (e.g., 65% Cotton/35% Polyester) to ensure the hand-feel and durability meet your brand's specific requirements.