On a question that was asked somewhat regarding preventing/treating blisters, I got this thing being said by a reputed and a respectable climber (DavidR):
"Having 'duct tape', 'mole skin', or other adhesive products, and knowing how to apply them to prevent blisters in trouble spots."
And, frankly I have no idea of how to use/apply a duct-tape or a mole-skin. Can anybody please elaborate how to do it? And, what can I mess-up if I do that wrongly?