Boots have to fit well. When buying new boots try on several brands, looking for a fit that is comfortable and appropriate for the type of hiking intended. Feel inside for thick seams or irregularities that will rub against your foot. If boots are too loose or too tight they will cause problems as your foot moves or swells during the hike. Boots should be big enough to accommodate an insole and two pairs of socks. A steep uphill grade will cause heel movement in the boot while a downhill grade will cause pressure on the toes. Both actions can cause blisters. The latter can splinter toenails, cut them short before the trip.
Good hiking boots will have a locking cleat by the ankle to allow for tight lacing in one part of the boot and flexibility in the other. For uphills the upper part should be tight. The toe end of bootlaces should be tight to prevent slippage on downgrades. New boots have to be broken in before you start a big trip. Wear them about town for progressively longer periods each day until they feel comfortable for the whole day. Starting a major hike with brand new boots could ruin not only your trip, but that of your companions.
Sock It To 'Em
Socks should be clean and dry. Sand or debris in socks will rub against the foot causing blisters. Wet socks make skin soft and prone to blisters. Hikers should wear a clean pair of socks every day on the trail. That means either bringing enough to last on long trips or washing and drying socks every few days. Inner socks should be ultra-thin and made of polypropolene, a fabric which wicks moisture away from the feet. Outer socks should be moderately thick and be made of wool which insulates even when wet.
At the end of a day's hiking it is a good idea to don a pair of light camp shoes to give feet a rest and boots a chance to dry out. Sandals are nice but may not be the best backup choice if boots become unwearable. Hiking out in sandals or flip-flops could expose your feet to many hazards in especially rough terrain.
Blisters can be prevented by protecting tender spots or pressure points with Dr. Scholl's Moleskin, slippery adhesive tape or adhesive foam padding. Application of tincture of benzoin (Friar's Balsam) to the skin will ensure that adhesive protection will not work loose even under wet conditions. Loose or bunched up coverings can add to problems.
When a hot spot or blister has already formed, Friar's Balsam or adhesive protection should not come into direct contact with the damaged skin. Rather the blister should be allowed to poke through a "doughnut" cut in moleskin to alleviate pressure. Once enough layers are built up, the doughnut hole should be covered with adhesive or a final layer of moleskin for protection.
Prevention The Key
Water blisters, once formed, should not be drained as they will then be open sores susceptible to infection. If blisters break the area must be kept clean and the sterile dressing covering the wound must be changed daily.
Once a blister forms, treatment and protection of the dressing becomes more complicated. Prevention should always be the goal.