Generally, it's advised to hire a Trademark attorney to guide you through the process of apply for a Trademark or Service Mark. Alternatively, some people use low-cost services such as LegalZoom to file for a trademark. Applying for a US trademark with the US Patent and Trademark Office (USPTO) yourself requires knowledge of Nice (as in Nice, France) trademark classes (e.g., Class 041 is for professional coaching services in the field of business and personal development).
If you wish to apply for a trademark in European Countries, the European Union Intellectual Property Office facilitates applying across EU countries.
If you wish to apply for a trademark across more than 100 countries using a single application process, the Madrid System administered by the World Intellectual Property Organization offers such a service.