Survey the land that needs clearing and make note of the location of any large rocks that would otherwise hamper the dozer during use. Remove these rocks prior to hiring the dozer to save rental time, thus rental money. Use a heavy duty pickup truck and tow chains to remove any large rocks. The displaced rocks can be hauled to quarries, busted up or used in other landscaping projects.
Clear out any underbrush or foliage. This will make it easier for the dozer driver to see and identify the trees that need to be cleared. Check the ground in the area, as well, to make sure there are no large crevices or chasms that could result in the dozer becoming stuck or stalled.
Mark any trees over 7 feet tall or 2 feet in diameter: make a horizontal line around the truck at about shoulder height. Use this mark as a guideline to cut the trees at this point. Doing so will make it easier for the dozer to uproot trunks and reduce the chances of a tree falling backward toward the driver and resulting in injury. Saplings are of no concern.
Remove the trunks manually from the area, out of the dozer's path. Have bystanders stand at least 20 feet away from the dozer as it works for safety's sake. Fire up the machine and lower the shovel until it's about 1 foot from the ground. Slowly approach the first tree and let up on the brake, allowing the dozer to slowly push forward and topple the trunk. This ensures the dozer rips as much of the trunk's root system from the ground as possible, to prevent growth.
Repeat until all the trees trunks have been uprooted. Cut the trunks into smaller sections with a chainsaw and insert the wood into a wood chipper to reduce them to mulch that can be used around trees and shrubs.