a good sort of neutral place to start is to put you heel on your pedals and you should be able to pedal backwards without your heels leaving the pedals... fore aft position so that a string with weight on it and held at the side of center of knee joint is in line with the pedal axle at 3 o'clock position... you need to do some jiggling up down back forward because when you move the pedal fore aft you move it closer and farther from the crank axle but in the end you need to end up with what i described above.
from that neutral position you can make slight adjustments to get it just right for your personal liking.. better to have the seat high a little too low than too high as you can get over use injuries from it being too high..