In the beginning when the hair is dark and coarse you want to use the largest spot size available at the highest setting. The Apogee I believe has a max spot size of 15mm. The Candela lasers have a max spot size of 18mm.
After a number of sessions, generally 2-3 with most areas of the body, but the face takes many more. Generally 10 proper treatments vs. 6 for other body parts.
So after the hairs become lighter and finer in my practice I would reduce the spot size and increase the joules. I use a candela so start at 18mm and 20j ideally. Reduce to 15mm and >25j and the last treatment will sometimes be reduced to 10mm with another increase in joules. This is to treat the finer hairs.
You are going to want a numbing agent on the face and be prepared for a long treatment schedule. The face is the most difficult area to clear.
I hope this was the kind of info you were looking for.
Ale, I just read in another post that you are female. These guidelines are true for areas of hair that are dense like male facial hair. Treating females, the main concern is induced growth. Its best to protect the surrounding areas with ice so the heat from the laser does not transfer to the surrounding areas inducing growth. Female facial hair is very tricky. Unless it is thick and coarse electrolysis is the best modality to use.