I have hoarding tendencies and my house used to be a nightmare... ESP with a hoarding husband!!! I had to become master organizer so I now have a very neat home and everything has its place. I help other people with nightmare houses get their homes under control. I start with the main rooms... Usually living room and then kitchen. Start with garbage and collect all all obvious garbage. Get bins and designate a bin for clothes, one for knick knacks, one for stuff that belongs in other rooms.... Get lots of bins and find themes. Practically empty the room except for furniture. Do a deep clean (vacuum, mop, etc) and then slowly bring things back only if there is an obvious home though (eg, all DVDs go in a certain drawer or shelf, all video equipment goes in the same spot, etc. ) often buying baskets or more shelving is needed!!! The stuff that you have left is in the nightmare bins to deal with and perhaps gets purged or belongs in a different room (which needs a specific home when u get to those rooms). When you are finished one room you will feel so good, then you can tackle another room eventually. You can also take stock of what you have this way and stop buying duplicates. The key is that everything has to have a very specific home... Even thumbtacks!!! With each item think to yourself , "if I were to look for this item, where would I logically look for it?". So, thumbtacks would be found in a home office area... Voila!!!
So, the homes I have done are TOTAL hoarder places.... I'm talking one time I had to shovel the contents from under her couch cushions it was that bad.... Toilet and tub were black with mould. Was brutal....but gratifying.... And I didn't get paid!!!!!! Haha!!!
Hopefully that helps!!!!