How do I pick and choose which papers to keep and throw?

I am a writer and a list maker. Papers are sacred because I pour my heart out onto them. I have always had trouble being a paper hoarder. I am overwhelmed with how many papers I have. I have purchased a filing cabinet, dividers, and hanging holders. I've started by dividing loosely by "Personal" (i.e. my journal, my ideas, my planners, memorabilia and more), "Professional/Serious" (taxes, school planning, job paperwork, apartment paperwork, bills), "Instructions" (from everything I've ever owned almost), "Action needed" (a credit card program I need to cancel, Someone's mail I need to return because it was accidentally sent to me, and more), "Receipts" (I will throw away after I enter them online), "Recipes", "Fitness" (my forms tracking my fitness and informative tips). There are more papers that won't fit into those categories. I read in an article that studies show people on average only go back and use 30% of the papers they keep. I would like to narrow this down! Any tips please? Have you ever done anything like this? I can't afford a professional organizer or one of those nifty $200 scanners that place them in categories for you.