You may also want to see which local malls have walking groups and join them - that way you will be well prepared for the marathon mall day. Shopping involves walking, standing and carrying. Most store floors and sidewalks have a base of concrete and will stress your feet. Select your shoes for cushioning and support as you twist, dodge and stand in lines while carrying packages. A purse can throw off your walking posture and is just another thing to carry.
Posture is important for walking comfort.
Consider a little wheeled cart or planning frequent trips to the car to deposit your booty. Use pick-up or delivery service whenever you can. Dress for comfort in loose clothing, with nothing tight or constricting. For outerwear when going to an enclosed mall, wear a light jacket to dash from parking to the entrance. Once inside you will be shedding your outer layers and you don't want to have to lug around a heavy coat.