I would recommend 10 mg - 15 mg mixed amphetamine salts for someone with no tolerance. I seriously advise not to take them daily for long periods of time, even if they are prescribed to be taken daily. Amphetamines are most efficacious when used as needed, as daily use encourages a very quickly rising tolerance to the pleasant effects and neurotoxic damage. So use them recreationally if you want, fine, but please don't make it a habit.