A good resource is the Small Business Administration. If your county has a Regional Developement Council, they are a good resource for starting a new business.
Some people think that just by putting an ad in the paper, voila! It all happens. But you need some legwork done.
Here are some sites on How To Start A Cleaning Business:
Cleaning Service Business Idea - Entrepreneur.com
http://ezinearticles.com/?How-to-Start-a-House-Cleaning-Business-under-$200.00&id=5122
How to Start a Successful Cleaning Business
Also do not get caught up in buying a separate product for everything. You can make your own cleaners that are very effective and not expensive.
Fact Sheet: Safe Substitutes at Home: Non-toxic Household Products Healthy Home - How to Make an Healthy, Environmentally Safe Home.