If you're just a random acquirer and things do not get put in their place, you might not realize how much of one type of item you have.
As you are sorting it might be helpful to put things of one category together temporarily so you have an idea of just how much of one type of item you have. Then, ask yourself, "How many of these do I actually need?"
For example, I like candles and candleholders. I store them all together in my "Candle Department" now. As I tidy, if I find misplaced candles, I return them to the Candle Department. If the candle area is full, then I know I need to purge.
Also, if I want a new item, I know I must get rid of an old item. That's how you stay organized: One in, one out.