Above all, you need to commit to staying the course, much as you would in building any important business relationship. There is an important and necessary linkage between marketing and PR, for public relations strategy and tactics flow from the thinking that goes into marketing planning. Public relations has a hard time succeeding if it can't reflect a consistent identity and approach to your markets. A PR plan may include advice that is useful in the absence of a marketing plan, but shouldn't be a substitute. No organization functions well or long without a guidebook, usually a comprehensive plan, a budget, and set of objectives developed from self-knowledge and market research.
Good research goes beyond accepted wisdom.
It checks the foundations of your assumptions, and serves as an excellent reality check. Sometimes, cherished positions are challenged. Face it, the people who get covers on national news magazines are either saints, politicians, billionaires, or axe murderers. On the other hand, products and services don't sell until people know about them. Work with an experienced PR person to develop realistic goals based on reasonable expectations for your situation.