hi there ,the best way to learn is get a job with a cleaning company,theres nothing like learning hands on.Some people on here may feel i am way off but i think if you know the work involved and enjoy it, know what your staff have to deal with and how long a job takes in all situations, then you can work with your staff, know how much work you can expect any one person to do.Reading from a book is no substitute for doing the real thing