Cover the parts of your feet that are being pinched by your heels with moleskin, soak your feet in water, and then wear your heels for a few hours. Moleskin is basically a more comfortable bandage that comes in sheets that you can cut into any size. One side is sticky and one side is soft. It protects the areas of your feet that hurt when wearing your heels, which is typically where blisters might form. Dampening the moleskin and then wearing your shoes will help the insides of your shoes to mold more quickly to the shape of your foot.
Keep silica gel packets in your shoes when they’re not being worn. Have you noticed after purchasing a pair of new shoes those little white packets containing tiny clear balls inside your shoe box? Those packets contain silica gel which absorb moisture and keep your shoes from shrinking. Hold on to those packets instead of throwing them away and stick them in your shoes when you’re not wearing them. You can ask a shoe store associate for extras, if necessary.