Start by reaching out to the businesses that are the most likely to have a need for your services and are large enough to pay for them. I recommend you target other home-based businesses, with an emphasis on ones that have been in business for some time and have sufficient revenue. For example, look for businesses that provide products or services that take them away from the home office a great deal or whose owners are not focused entirely on knowledge-work, such as work that has them computing all day and doing related paperwork.
A caterer or plumber, for example, may be more likely to need outside support than someone who does medical insurance paperwork. You'll need to make some assumptions about your best prospects and then contact them by phone and follow up in person or by mail. Be sure to have a terrific website in place so the prospects you contact can check you out on the web.