Similar to Connecticut, Mississippi, Nebraska, New Mexico, North Carolina, Oregon, Tennessee and Wisconsin
The Secretary of State orders names to be printed on the primary ballot if "in the Secretary's sole discretion and consistent with party rules, that the candidate's candidacy is generally advocated or recognized in the news media throughout the United States or in Maryland."
Thus inundating and trolling your local state news media by mail, phone, social media, and radio, may be a good strategy to get me on the Republican Presidential Preference Primary Ballot in Maryland.
We all know how difficult it is to get the attention of national media - First local then national - grassroots then mainstream.
If the Secretary's "sole discretion" doesn't choose a candidate, then a candidate may petition the Secretary for placement on the primary ballot.
A candidate must "submit to the State Board of Elections a petition containing the signatures of not less than 400 registered voters from each congressional district."
Maryland has eight congressional districts - hence 3,200 signatures are needed
In the 2016 primary the Secretary of State "determined that only those individuals who have appeared in nationally televised debates prior to January 27th, 2016 will have his or her name placed on the primary election ballot for the 2016 Presidential Primary."
The Primary is April 28, 2020