None. Crying is not a disease, a lot of normal babies cry significant amount of time per day. However one has to ensure that baby is not hungry, does not have wet dirty diaper and does not suffer from any sickness for example: colic, allergies, diaper dermatitis, meningitis and many others. In such instances treating disease will help to decrease crying spells.
Great question! If i knew the answer to this, i would still have most of my hair! each baby is different with each own temperament. There is no cookbook best way approach to this. Best you can do is make sure the diaper is dry, the baby is fed, the temperature is comfortable and let it be. Sometimes, babies just cry for no reasons...I will retapp this to get other opinions. Good luck.