This is what you would learn to do in a mountaineering class. Hikers get lots of blisters. Go to any outdoor sports shop and get moleskin. It has adhesive backing. Cut a circular piece a little bigger than the blister and stick it on. The moleskin is meant to stay on until the blister heals, at which time it will fall off with the dead skin. The moleskin will cushion the blister and keep it from rubbing until it can heal on its own. Do not pull the moleskin off. It will come off on its own. Be patient. You really should not pop a blister, even with a sterilized needle. Your feet are in contact with bacteria all day. It is a great way to get an infection. And it is not necessary.