Talk with local Real Estate Companies, Banks, Credit Unions, and Owners BEFORE investing any money into this adventure. Find out if there is a need in your area, or are there already too many people and companies offering this service.
The "Foreclosure Cleaning Business" is pretty well saturated in most areas of the United States. Do an Internet Search for "Foreclosure Cleaning" or "Foreclosure Cleanout" and look at the hundreds of companies trying to sell you a Program or Course or Get Rich Quick Scheme dealing with Foreclosure Cleanups.
Many people spend $50 to $500 on these "Courses" and "Programs" that they buy off the Internet, then find out that there is no business to be had. And those Course Expenses do not cover the costs of Business License, Liability Insurance, Equipment, etc.
Again, check first with the people and companies who control and own the Foreclosures in your area, to determine if there is a need.