Complementary feeding should begin at 6 months of age when breast milk alone is no longer sufficient to meet nutritional needs. Signs a baby is ready include holding their head steady while sitting, opening their mouth when others eat, and appearing hungry soon after breastfeeding. Complementary foods should start liquid and gradually increase in consistency, while continuing frequent breastfeeding. A variety of nutrient-rich foods should be introduced slowly and hygienically to provide balanced nutrition as the baby grows.