Wash your hands thoroughly with soap and water

Dip clean cloth or gauze in warm water and wrap it around your index finger 

Carefully open the baby's mouth and insert your finger inside

You can open the baby's lower lip to enable opening of the mouth

Move your finger circularly over the tongue while being careful not to slide your finger over to the baby's throat

If there's any teeth present, carefully clean the teeth with gauze

Softly rub your finger over your baby's gum and on the inside of their cheeks too

Lastly, while cleaning the tongue and mouth, make sure to check for any stubborn thick white coating that wouldn't leave the surface in spite of wiping. It might be an oral thrush and might need medical attention.