First, join the Building Service Contractors Association International--BSCAI (http://www.bscai.org
). That's the association representing janitorial and custodial companies. Disclosure: I worked for BSCAI for 8 years--writing many of its books, editing its monthly magazine, editing other books, developing certification tests, etc.
Second, get some hands-on experience. There are plenty of building service contractors across the country. Get a job with one of them. That shouldn't be difficult. Labor turnover is a huge problem. For full-time employees, it averages around 40% a year. For part-time employees, it's over 100%. So most BSCs, at most times, will have vacancies. Find out what the job is really like. Find out how to market for business. Find out how to deal with unhappy customers.
Find out about bidding and estimating. That's a weak point with many BSCs, especially start-up ones. And just because someone else is charging $x to clean an office doesn't mean that you should. Your cost structure--guaranteed--will be different than theirs. Learn about marketing. Learn about niche markets. There's a lot more money to be made in niche markets--whether it's medical offices or flood cleanup or restaurant cleaning--than in the generic office cleaning. Learn about financing--how to pay for the equipment--the vacuums and floor scrubbers. (However, lean about cost structures. You'll find that about 70% of your expenses are labor expenses.)
Spend 6-12 months (minimum) doing that. You'll have a good sense of what you're learning and what you still need to learn. Then you'll be prepared to take the next step.
Hope that helps.