Take numerous samples.  Conditions may vary in different parts of the field, farm or lawn.

Check at least one sampling point for every 4 acres.  Then compare with a control sample taken from a nearby fence row or similar spot of known good tilth.

Place six or eight samples side by side to detect compactions in different areas of a field.

As the sampler is pulled from the soil, there may be a light chaffing or smearing.  Using a pocket knife, gently shave it, from the bottom upward, while holding the top of the core with your thumb to make sure that the core does not break.