how to use the heater

Should turn on the heater 24 hours?
because hot water heater after waiting to wait 15 - 20 minutes to have hot water to use, many families often have the habit of turning on the heater 24 hours a day to avoid waiting. however, this approach is controversial because of the high cost of electricity and potential safety risks.
How to use electricity saving water heater in winter?
when the weather gets cold, the heater will be used by more families. however, there are quite a few families who are making mistakes when using hot water bottles, causing the electricity bill to skyrocket