None, that book would be another piece of clutter. I am only half joking here, buying more stuff when you want to declutter is a bit contradictory. Do you rea

None, that book would be another piece of clutter. I am only half joking here, buying more stuff when you want to declutter is a bit contradictory. Do you really need a book about decluttering? If you really think you do, or if you really love books, then go buy that book, but the idea of "I want to get into X, let's buy something" is, I think, an important source of clutter.