입다 means "to wear on the body"
치마를 입다 to wear a skirt
양복을 입다 to wear a suit
신다 means "to wear on the foot"
스타킹을 신다 to wear a pair of stockings
부츠를 신다 to wear boots
cf.
쓰다 means "to wear on the head or face"
모자를 쓰다 to wear a hat
마스크를 쓰다 to wear a mask