It's normal for leather boots to feel a little stiff when you bring them home. Breaking in boots so they're comfortable and blister-free takes time, especially if the boots are constructed from heavy leather. There's really no way to speed up the process, but a little patience and persistence pays off with stylish, long-lasting boots that serve you well for many years.
Place soft foam, gel or rubber inserts or insoles inside the boots to provide extra cushioning during the break-in process.
Wear the leather boots around the house for short periods of time. Go sockless the first few times. Notice areas where the boots rub or pinch, then protect those spots from rubbing with a bandage or self-adhesive moleskin.
Break in the soles gently by doing a few deep knee bends or squats with the boots on.
Cushion your feet with two pairs of sturdy cotton socks when you wear the boots outdoors for the first time. Cotton socks work better than wool or synthetics, which tend to slide inside the boot.
Limit walking to short periods when you wear the new boots outdoors for the first time, then gradually work up to longer periods of time. Stick to a flat terrain or gentle hills initially and avoid steep slopes or rocky, gravelly, uneven surfaces. Take off the boots at the first sign of discomfort and don't progress to longer periods until the boots feel comfortable.
Take your boots to a shoe repair shop if certain areas continue to rub after the boots are broken in. A professional can use specialized devices to stretch the boots gently in those tight spots.