You could conduct the seminar as a sole proprietor. As a tax expert, you should understand the tax implications of doing so. There are various forms of business entities in Missouri, with differing implications for personal liability. I recommend you consult with a business attorney.
My comments are general in nature, are not legal advice as to your specific issue, and do not establish an attorney-client relationship. Disregard this solicitation if you have already engaged a lawyer in connection with the legal matter referred to in this solicitation. You may wish to consult your lawyer or another lawyer instead of me. The exact nature of your legal situation will depend on many facts not known to me at this time. You should understand that the advice and information in this solicitation is general and that your own situation may vary. This statement is required by rule of the Supreme Court of Missouri.