1. Shop for your body type. Broad shoulders? Avoid racerbacks in favor of V-necks. Petite? Opt for long pants over cropped styles.
2. Buy clothing tagged for your activity. For yoga, comfortable, roomy apparel is best. Runners need extra support.
3. Do a few jumping jacks in the dressing room. If clothing restricts movement or rides up, this is the time to find out.
4. Surf the Web. Many of your favorite online retailers have easy-to-use sizing guides and liberal return policies.
5. Embrace synthetics. These high-performance fabrics do everything from keeping your body cool to protecting you from the sun.
6. Go seamless. These designs limit chafing.
7. Hem your workout pants. The right length will keep you from tripping and leave your legs looking leaner.
8. Be gentle. Clean workout clothing with a gentle detergent, preferably a sports wash, and cold water; hang dry to prevent fabrics from breaking down and becoming misshapen.
9. Replace your sports bra. Recommended: every 12 to 18 months to ensure proper support--and comfort.
10. Buy in bulk. When you find a piece you love, snag a second (or third) one.