Please keep in mind that starting a cake-selling business that it is a business - all expenses and income tracked, bookkeeping, license(s), health department inspections, food safety course, taxes, liability insurance, operating expenses until you show a profit (1 year? 2 years? more?), etc. etc. etc. It isn't just baking and decorating cakes. Your sister's friends are just paying you a compliment. They have no idea what is involved in running a cake business.