To care for a String of Bananas (Senecio radicans), provide bright, indirect light, ensure well-draining soil, water sparingly after the soil dries out, and fertilize lightly during the growing season. 
Here's a more detailed guide:
Light:
Bright, indirect light is ideal .
Avoid direct sunlight, which can scorch the leaves.
A sunny window: is a good location, but ensure the plant is protected from intense afternoon sun. 
Watering:
Water sparingly, allowing the soil to dry out completely between waterings. 
Overwatering can lead to root rot, so it's better to err on the side of underwatering. 
Check the soil moisture: by sticking your finger into the soil; water only when the top inch or two feels dry. 
Soil:
Use a well-draining succulent or cactus mix .
Avoid heavy, clay-like soils: that retain too much moisture.