Not that I wouldn’t still recommend this book, but…
Below is an excerpt from Robert Wearing’s The Essential Woodworker: Skills, Tools And Methods.
To learn to gauge, first put a length of wood in the vice, projecting about 50mm (2in.). Set the gauge to approximately the size required and tighten the screw finger-tight only, adjust to the correct size by tapping one or the other end of the stem on the bench top then tighten the screw fully. The stock of the gauge is pushed by the thumb and further held with the index finger. The other fingers curl round the stem. The gauge is applied to the work on the flat side of the stem, the pointer well clear and the fence pushed against either the true face or the true edge. The gauge is slowly rotated (Fig 49) until the pointer just touches the wood and the pressure is taken on the corner of the stem. Maintain this angle and make a stroke, with the pointer trailing and the fence firmly pressed into the work. Repeat on the end, the other long side and the other end. Always gauge from the true face or the true edge. If there is any doubt, shade the waste diagonally with a soft pencil.
Skilled workers will be seen holding the work by hand in a variety of peculiar ways. Beginners should use the vice wherever possible, learning first of all merely to gauge, then when proficient they can try out different methods of holding. (Wearing 37).
Wearing, Robert. The Essential Woodworker: Skills, Tools And Methods. Fort Mitchell, KY: Lost Art Press,