I'm hyper-organized, to the point where if someone moves a vase in my house when I'm not there I know it as soon as I walk in the door. Also I've moved a lot in my life & that's helped me keep things streamlined.
That's a cool link Lori, & has some great ideas. There are some TV shows too, I think on DIY. If I were you I'd start w/one room in the house & not move on to another room until you've finished the first. Don't be impatient, & don't panic about it, just do it methodically & don't expect to finish quickly.
Something I learned on one of those shows is to make three piles, a keep pile, a throw away pile, & a maybe pile. After you organize/store the keep & toss the throw away, you go through the maybe & decide if/what you want to keep & whether you have room for it.
It might be less intimidating for you if you contacted your local garbage hauler & asked them if they could come take away a big load of stuff as needed, & how much they'd charge.