Applicants are not obliged to hire an attorney for assistance with trademark filings, although it may be desirable to employ an attorney who is familiar with trademark matters, since their might be opposition and requirements that are confusing and in terms that are not easy to understand.
Must of the time people need advising in their filling and need to follow some instructions depending on the country that wants to register the trademark/patent or an IP matter, having in mind that every country have different requirements and jurisdictions.