How will i know what my baby needs?

Practice: Soon you will be able to distinguish the hungry cry vs the pain cry vs the tired cry. But this takes practice, so don't be discouraged in the beginning. Look at the clock when your baby begins to fuss. Has it been 2-3 hrs since feeding- try feeding? Have they napped recently? Have you checked the diaper? Do all these things before attributing the cry to just normal baby fussiness.

Baby needs: The baby will get fussy or cry if he/she is hungry, has dirty diaper, sick, uneasy from gas, constipation etc. Make sure baby is fed, burped well, diapers are changed frequently. If baby still fussy make sure does not have fever or other symptoms that require medical attention.