A protocol, is a set of steps that you follow to participate in collecting data. The protocol ensure that your data is collected the same way as everyone else who is participating, so that your data quality is consistent with other participants.
“Free standing”: If a rain gauge is too close to a building or other solid surface, precipitation may bounce off of other surfaces and fall into the gauge — making it appear like more rain occurred.
Homogenous surface area: a site location where the ground cover is the same across the area in which you are collecting measurements. The area could be low cut grass, unmaintained green surface (tall weeds), paved area — as long as the surface is the same everywhere you take a measurement.