No marketing plan compares to building a house without a blueprint: you might get the job done, but it’s completely accidental. I don’t know you, but I don’t want to rely on accidents. I want a reasonable plan so I know what steps to take and when to take them.
So, how do you develop an effective marketing plan? You learn from successful people and see how they do it. Whatever your niche, someone has been there to do basic work for you.