Two things you need to check:
1) Zoning ordinances--a home office (e.g., where the self-employed person, for example a tax preparer, deals primarily with paperwork) isn't quite the same as a place where the primary business activity consists of clients coming to receive services (e.g., a dive school or a beauty salon). Make sure that zoning laws allow you to legally carry on the sorts of activities you will be engaged in at your place of residence.
2) Insurance--your homeowners policy may not cover you for accidents that could occur in/around your swimming pool, for example, if you are engaged in commercial activity at the time of the accident. Make sure your agent writes a policy that will protect you in the event of an accident.
The other thing about home-based businesses is that you need to keep excellent records for tax purposes. You need to calculate portions of utilities payments (usually according to square footage of the home-based business), and any other expenses you incur for the maintenance of the home office. Some localities have rules that stipulate a separate walled area rather than just a corner of your living room, for example, so find out about that as well. You also need to maintain an inventory of all teaching materials (such as DVDs and teaching aids) as well as student dive equipment that your business owns. Consider buying office equipment in the name of your business as well, and keep track of expenses such as office supplies, postage, phone bills, mileage when on company business, etc.
