There's a fine line between "having stuff" and having so much stuff, you can't utilize your home like you're supposed to — bills and magazines on your dining table preventing you from sitting down for dinner or so many clothes (some still with tags on) that you've given up on trying to put anything inside your closet. In the book The Hoarder in You ($13), author Dr. Robin Zasio lists the signs of hoarding tendencies to watch out for.
The more of these you can relate to, the stronger your hoarding tendencies are. Don't be alarmed if some of them resonate with you; chances are many people share one or more of these signs. What you need to do is be aware of them and start on your journey to reduce clutter one item at a time.