The heel and instep of your foot should fit snugly (not tightly) within the boot, your heel should not slip up and down. Your toes should have room to stretch out and flex freely as you walk, this means you need about 1.25 cm of space between your longest toe and the tip of the boot. Stand on one foot at a time and wiggle your toes. Be extra careful with the fit of narrow-toed compared to round or square-toed boot styles. They can cause foot problems for you later in life, such as bunions, corns and maybe arthritis. If your heels wear at an irregular angle after only a few weeks, you may have a problem that a podiatrist needs to solve. If they wear irregularly after several months it may be normal. Very few of us walk with our weight evenly distributed. Stand on tip toe, the boots should bend where your foot bends. Buy hiking boots slightly larger than your normal size to allow for your feet swelling on long hikes.