Another example is having a portfolio from other sources, such as working on the publications of a nonprofit organization. Or your parallel experience might be in an allied field, such as public relations, or in a particular lane of journalism. You probably know that more journalists work for specialty or industry publications than at newspapers. Professionalism comes in a variety of ways. You might be surprised at how casual certain job-seekers can be, beyond looking the part at an interview or sending resumes around in a mass mailing.
Persistence is probably the area with the biggest payoff.
Covering the traditional bases is relatively easy. Adding a dimension of creativity to the search, such as finding a different set of contacts at your target organizations, is where the challenge lies. Write to people whose work you admire. Ask them for advice. Ask them how they broke in.