Choose an unclear gender (other, agender, etc) and your data becomes less useful. Marketing campaigns are based on broad categories, like male or female, so choosing neither lowers your data’s value.
Similarly, lie about your education and your employment. Pick a made up job, be a wizard, or a spaceman. Jobs, again, are wide categories, so nonsense jobs, the more niche the better, the less they have to market things to you.
In theory you can do the same with hobbies, but three points of data, even made up data, is sellable somewhere.
Lie, of course, if you can. I’m sure there are more denizens of Hell on Facebook than the real place.