If there are visible stains, pre-treeat them with a gentle detergent and warm (not hot) water before hand washing. Blot the stain gently with a clean washcloth - don't rub!
Fill a clean sink with cool or warm (again, not hot!) water. Add a small amount of gentle, organic, chemical-free detergent - preferably one specially made for fabrics often used in fine lingerie (like delicate silk and lace, and stretch materials like polyamide and elastane). Submerge the garments, gently swish them arround, and let them soak for 20-30 minutes.
Drain the sink and rinse each piece gently with cool water, to ensure detergent washes out. A good quality, delicate wash detergent should wash out quite easily.
Dry it right.
Lay your garments flat and use a towel to gently pat out excess water.(Never twist or wring!) Then transfer them onto a clean, dry towel or drying rack to air dry. Leave them in their natural shape to avoid excess stretch.