Elizabeth Gaskell, in Cranford - about which excellent book more, another time - observes that most people have odd habits of frugality, for instance in their use of candles, or writing paper, and that there are certain areas where they will go to great lengths to save money, though they may not always be as frugal elsewhere.
Reading this reminded me of my first boss, who told me once that thirty or so years' earlier he had resolved never to buy a biro, and never again did so. He had a nice fountain pen, used for signing letters and for personal correspondence, but for everything else he made a habit of using free pens, picked up whenever they were on offer, and using those. I usually seem to be using a free pen acquired at some conference or other, and perhaps I have also absorbed the notion that pens are something which one should not have to buy.
For another, my mother-in-law, who is extremely careful and orderly in all things, was the first person I had ever met to make rubber bands out of old rubber gloves. I always seem to have a plentiful supply of rubber bands lying around, but do occasionally follow her example, although mine always have jagged edges and look a lot messier and more uneven than hers.
I suppose this is further evidence of how much we are all creatures of habit; I'm not aware that I have any particular frugal ways myself, except perhaps for an occasional fondness for second-class stamps, but perhaps I wouldn't know it; I'd be interested to hear of any other habits that others have observed in themselves or other people.