Stand the pole vertically on hardware installed on a concrete pad or in a hole dug to the depth required by the pole manufacturer. Adjust the pole until it looks plumb to the eye.
Set a 4-foot level against one side of the pole. Note the location of the air bubble in relation to the two lines marked on the horizontal level vial. Move the level to the opposite side of the pole. Note the location of the bubble on the second side of the pole.
Slide cedar shims under the base of the pole -- concrete installation -- or in the sides of the mounting hole -- buried in the ground. Ensure the shims are aligned with the sides that held the level. Adjust the shims until the vial bubble sits in the same location on both pole sides. The bubble will not sit directly in the center of the vial.
Move the level to a side perpendicular to the first two sides. Repeat the process on leveling and shimming until the vial sits in the same location on each side of the tapered pole.
Tap the back of all shims lightly with a hammer to seat them before completing the installation of the pole.