The first step in simplifying is learning to be more organized. You have got to be organized to move forward to simplicity. For me, being organized doesn't come naturally, it's a process of clearing out both the literal and figurative cobwebs.
Being consistent isn't easy either because as soon as everything is in it's place, along comes something new out of place, and you have to begin it all again. Being consistent is probably the hardest part for me.
Why we hold onto things like we do is the great mystery, I suppose. You can hold onto things physically, yes, but we also hold onto the past and present in our minds, which is another kind of cobweb. It follows that as you seek a simpler life, every aspect of your life is affected, as it should be. You begin to use what you have, and amazingly find that a lot of the time it's enough, it works. You learn to move forward a little at a time, and that seems to work, as well.
You trim a little here and a little there, you donate things you can't use anymore, you let sentiment take a back seat and let go of something you haven't used for years. Clearing out the cobwebs isn't easy, but it's worth it.