Be mindful not to loosen dirt at the bottom of the footing. Use a plate tamper or shovel to compact soil if loose.
If the elevation of the footing drops more than approximately 6”, step the footing down by making a shelf where the footing will be lower. This keeps the footing level while still following the grade.
Level the top of the gravel footing using a long level or line level. Smooth the surface with a garden rake and plate tamper.
Use a rotating laser and receiver for long distances to improve accuracy.
Continue with the second layer, ensuring the wall is slightly moving back towards the bank. Ideally, the wall should have a backward angle at approximately 1/2" to 1'.
Rotating longer stones to periodically face into the bank will give you more options for fit and will provide more stability to the wall once backfilled.