Use a heavy rake with its tines facing up to break through any high spots on your driveway. Because prolonged use of the driveway will lead to holes and troughs caused by vehicles, your driveway may get bumps in certain areas. Push through these bumps with the rake and gather the gravel into a pile in one central area.
Take shovelfuls of the gravel from the pile you've created and distribute the gravel evenly in the holes in the driveway. After you've filled each hole, smooth it out with the heavy rake. If your driveway is too large to do the job by hand, or too pitted to complete the job in a reasonable amount of time, you'll need to use a lawn tractor.
Rent a grading blade at an equipment rental center. These blades are heavy iron and are designed to be towed behind a tractor. Hook up the blade to the towing bar of your lawn tractor with its tow chains.
Drive around the driveway on the lawn tractor, towing the grading blade behind you. It is heavy enough that it will grade the driveway on its own, so there is no need for you to manually even bumps and fill holes. Make several passes around the driveway to loosen and even the gravel. This process may take a significant amount of time, as a badly pitted driveway will require several passes of the grading blade.
Rake any ridges or high areas left by the grading blade with your heavy rake to smooth out the driveway.