Excavate the site using a shovel. The depth of the excavation should be equal to the height of the pavers, the thickness of the sand and aggregate base layers. Excavate to a depth slightly deeper than your calculation. The difference can be made up with base filler.
Remove any large rocks or roots from the area. Flatten the excavated area using a plate compactor.
Place stakes at intervals surrounding the excavation. Use a line level and tie string between the stakes. The more strings the better, as these serve as your points of reference to ensure the correct depth and level of the base.
Use crushed rock or another, similar aggregate as your base. Spread the base throughout the excavation area. Be sure that the base extends past the intended boundary of the finished project by at least a few inches.
Use a ruler or tape measure to check the height of the base back to your string. You want the base to have a slight grade in one direction for water drainage. The grade should be about 1 inch for every 8 to 10 feet.
Use the plate compactor to level the aggregate base. Check the height of your base regularly. Once complete, you can remove the strings and stakes and begin setting your pavers.