hi there,
whilst you can learn at courses, i strongly believe that getting your hands dirty on the job is the best source of learning, along with talking to people already in the business.
ive been in contract cleaning for over 5 years on sales and have given all that up to go self employed, and we are running to sides, our build clean side and special projects.
whilst the learning curve can be steep we are making a profit and getting repeat business, so we must be doing something right.
regards
martin