I was going to recommend the Fly Lady.
For de-cluttering and heavy cleaning, the only thing that has worked for me is to do one room/thing at a time. For example, do your pile of bills until it's done. Then move onto the closet with the door that won't shut. And so on and so on. Starting and finishing one thing can be so liberating, especially if you've been staring at messes all over the place. Plus, you get a great sense of accomplishment and motivation to move on to the next "thing".
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