If the applicant does not know much about patent-related legal knowledge and lacks patent application experience, then entrusting a formal professional agency is the most reliable way.
A formal patent agency needs to be registered in the China National Intellectual Property Administration Patent Office, so we can know whether it has the patent agency qualification by checking its qualification. Specifically, you can enter relevant information in the "Patent Agency Information Publicity" system in official website, China National Intellectual Property Administration.