Check your equipment before beginning. A breakdown resulting in a pile of snow sitting in the middle of a parking lot can be a disaster.
Plan ahead. If a large amount of snowfall is predicted, get out early and start removing the snow before it accumulates and gets too deep. Plowing a lot full of deep snow is possible, but can be very time consuming.
Set a specific goal in terms of how much of the lot needs to be cleared. If at all possible, plow the lot vertically. This minimizes the need to maneuver an awkward snowplow around short turns. Moreover, vertical plowing also reduced the time necessary to plow each lot reducing and lessens the amount of wear and tear on the truck and plow.
Adjust your plow to push the maximum amount of snow per pass. Generally, trying to make the second and subsequent passes in a lot requires trying to plow only about 1/2 the width of the plow per pass. Trying to start each pass with a full blade is counterproductive as snow falls off the side of the blade into the area already cleaned.
Push the snow as far off the lot as possible. This should be done to accommodate additional snowfall. Keep your speed down, especially in unfamiliar lots or when nearing curbs.