The most important thing that I've learned in the past few years is that you can't organize clutter. Seriously, you can't. You can buy out the entire container section of Bed Bath and Beyond and all you'll have is more junk.
I decluttered for almost a year. Every day for 15 minutes, I went into a different room and went through a small section and threw out everything I could. After I got my life together, I started donating. I would call up Am Vets and arrange a pick up date for a donation (they'll come to your house and pick it up from the porch). For the month before the pick up date, I would fill up bags and leave them in the dining room until pick up date. I've probably given away half of my belongings in the last year and it felt great!
Once your done decluttering, you're left with a very small amount of stuff that you actually need. Now is the time to start organizing. You have two options, you can head to the container store or Bed Bath and Beyond and buy gorgeous fabric covered containers to put your things away or you can head to the Dollar Tree and pick up a bunch of really well made containers.
Here are a few examples of how I use Dollar Tree containers (each 1.00!) in our house: