Ficus Benjamina, commonly known as weeping fig, prefers well-draining potting mix. They like bright light in the summer and more moderate light in the winter. As it grows, regular rotation of the pot will prevent one side from being uneven.
It's best to water weekly during the summer with room-temperature water, making sure it is watered each time thoroughly until it drains from the bottom of the pot (but discard the excess so it is never sitting in water). Always allow the soil to dry slightly between waterings, and if the leaves turn yellow and begin to drop, you may need to increase or decrease the amount of water. Check the root ball - if the roots are soggy, water the plant less often, and if they are dry, increase watering. Humidity and light levels affect the amount of water needed.
Ficus are sensitive to changes in their environment, and they react to these changes by dropping their leaves. The leaves will turn yellow and fall off, especially if you have recently moved your ficus to a new location. Thankfully, the leaves will grow back when the plant adjusts. If it has not been moved and it is still experiencing leaf loss, it may be reacting to a change in lighting conditions as the seasons change, or differences in its watering schedule. Be aware of the ficus' preference for regular habits and try not to deviate from them to avoid leaf drop.