use azelaic in the morning and tret at night
for tret use the sandwich method: wash your face, pat it dry, apply a thin layer of moisturizer, and apply a pea sized amount of tret over your whole face (avoid eyelids, lips and and corners of your nose) and wait until its been absorbed. after that apply another thin layer of moisturizer again
for azelaic: normal cleanser, azelaic also pea sized amount, moisturizer, sunscreen (spf 30-50)
dont spot treat with tret make sure to use it over the whole acne prone area