The grind setting depends on the grinder you are using.
Although generally, with an AeroPress or any filter brewing equipment, we would recommend a 'filter grind' which is slightly coarser than an espresso grind, so we can manually build up the pressure in the chamber.
With every coffee, the recipe is a little different so changes will need to be made as you go (ie: applying pressure earlier with a particular coffee and later with another).
Are you new to using the AeroPress? Or just want to learn more on how to brew your delicious filter coffee? Click here for a step-by-step guide.