Duct Tape adhesive is not designed for contact with skin, many people are allergic to some of the ingredients - namely rubber.
Also, in areas where you have delicate skin, if the adhesion is good (which it usually is not), you will need WD-40 or some other lubricant with good wicking properties (it is able to "suck in" to the sticky parts and do its job) to remove the tape.
Blister Block for areas that are prone to "friction blisters" (back of the heel, etc.).
Use moleskin (which is not expensive - buy it at
Walmart) for after a blister shows up (cut a hole in the center of the moleskin and it will surround the blister like a padded cushion and keep the blister from getting any pressure on it.
If your blisters are on the pads of your feet, they are caused by pressure. Shoes with better support and plenty of venting along with good socks may help you avoid these. However, if you are relatively sedentary in your normal life, then walk 8+ miles a day on pavement at DW, your foot pads have no calluses and you'll unfortunately develop blisters. No tape or other method will keep you from developing these types of blisters, however, the moleskin can keep them from getting worse or hurting as much.