There are a lot of suggestions on the Internet for how to stretch leather cowboy boots. Although most of them will work, many will damage the leather of the boots. To fit leather cowboy boots to your feet so they are as comfortable as a second skin is a process that takes a little time. The reward, however, of having a pair of boots that feel like they were custom-made for your feet makes it all worth the effort.
Clean the inside and outside of your leather cowboy boots with a warm, damp rag. Make sure you get into all the folds and creases if the boots are older and have been worn. Dip a new portion of the rag in warm water each time you wipe the boots so you are always using a clean section of the rag.
Use a fresh rag and rub it into the tin of saddle soap. You want to be able to see a layer of saddle soap on the rag. It will look like a soft wax coating.
Rub the saddle soap into the leather, beginning on the inside of the boot. Go far enough into the boot to get the tops of the toe. Completely coat the exterior of the boot, paying special attention to the sides of the boot where it is stitched into the sole.
Repeat Step 3 until the entire cowboy boot, inside and out, takes on a warm sheen and feels supple and almost damp to the touch.
Put on an old pair of the socks you plan to wear with your boots, and put the boots on. Wear the boots for at least one hour so the leather becomes warm.
Take off your leather cowboy boots and pack them with damp newspapers as tightly as you can, but not so much as to push the leather out from the shape of your foot that the leather is beginning to take on. Let the boots dry overnight and then repeat this process. After about a week, your boots should be stretched to fit your feet.