A 6-month-old infant is brought to the clinic for a routine check-up. The mother mentions that for the past month, the infant has had intermittent, dry, itchy patches on his cheeks and in the flexures of his elbows and knees. There is a family history of asthma and hay fever. On examination, there are erythematous, slightly scaly patches in the described areas. What is the most appropriate first-line management?