This is what I would do, which is of course not necessarily what you should do. It's roughly how I got started on clearing the full-of-junk back bedroom. It doesn't actually solve the questions about specific items - there are a lot of good answers from others for that. I'm posting more about the mechanics of how to cut the overwhelming task down to manageable bite-sized chunks.
- I would get a zillion identical boxes, the kind that stack flat until you actually need them. U-Haul book boxes, file boxes from the office store, whatever, but all the same. And tape to build the boxes with, if they're the kind that need tape. This is because identical boxes are easy to stack and pack in tight.
- I would grab a table - maybe the old kitchen table that you mention - to work on, and put it near the stairs. I would clear the table and the space around it, even if that means making bigger piles elsewhere.
- I would stack my zillion boxes near the table. I would also have a box of Ziplocs, a box of trash bags, and a box of packing newsprint (the kind you can get from U-Haul) there. Also a radio or CD player so that you can have some really good music.
- I would declare a "stack the boxes" corner. I would clear that corner, dumping the stuff in it somewhere else, even if that means, again, making bigger piles.
- I would declare a "stuff too big for boxes" corner and clear it, as above.
- Using the table as a work surface, I would pack almost every single thing that fits in the boxes, in the boxes. I wouldn't bother with sorting, with decluttering, with _anything_ but stuffing miscellaneous junk in boxes. Start with the heap nearest the table, and just nibble your way along. If stuff is already in mismatched boxes, either dump the stuff into your new boxes or stuff the boxes into your new boxes.
- As you box, stack the boxes in your "stack the boxes" corner. Slowly expand out from the corner to build a WallOBoxes. Put items too big for boxes in the "stuff too big for boxes" corner.
I pause to emphasize again: No sorting, no decluttering, no organizing at this point. No labeling of the boxes. You're just encapsulating the stuff into neatly stackable units. This is the "boxing" phase, and it's just preparation for decluttering, it's not decluttering. If you mix it up with decluttering, it will take much, much longer. A space full of junk can be boxed in a few hours; it could take a few months to fully sort and declutter it. The hours of boxing are an investment in greater comfort and efficiency for the months of sorting.
Some special cases while boxing
-- Things that are too big to fit in the box: Put these in the corner that you prepared for this purpose.
-- Things that are dirty, like muddy boots: Put them in the trash bags and then stuff them in the box.
-- Things that are flammable or otherwise dangerous: Put them aside somewhere safe.
-- Things that are both fragile and valuable to you: You could wrap these in the newsprint and put them in the tops of boxes where they're less likely to get crushed, or you could put them aside and, when you have several, create a "fragile" box. Things that are merely fragile, like coffee mugs that you aren't overfond of, can just get stuffed into the box and take their chances.
-- Things that are exposed food or wet or leaking: Trash them or put them aside. I say "exposed" food to distinguish them from things like canned soup, which I would probably just box.
-- Bunches of tiny things, like hardware or coins: Put them in the Ziplocs and put the Ziplocs in the box.
-- Things that you really, truly, genuinely, absolutely, know that you will need very soon. For example, if you're boxing in December, this includes the Christmas decorations. If you're doing this in May, it doesn't. These things, you can actually put into boxes designated just for this purpose, and label them, and stack them elsewhere. But I would make this category as small as humanly possible.
When you're done, you have a HugeWallOBoxes, and a HugeCornerOBigJunk, and hopefully more clear floor and wall space elsewhere in the basement. If the HugeCornerOBigJunk makes you crazy, I'd try to throw a tarp over it or put a screen in front of it.
At this point, you have the power to go through the stuff one box at a time. You could even take one box at a time upstairs, thus freeing yourself from the need to work in the basement.
There are many options for how to handle the stuff.
One thing that I did early was:
- Got a box of stuff.
- Got two empty boxes, designating one Trash and one Not Trash. You could perhaps have three - Trash, Recyclable Trash, and Not Trash.
- As fast as possible, I went through the box of junk object by object. For each object, if it was trash, I put it in Trash, otherwise I put it in Not Trash.
- Got another box of junk and continued. As the Trash box filled up, I dumped it in a trash bag. As the Not Trash box filled up, I put it in a new WallOBoxes, a foot or two from the old WallOBoxes, so I wouldn't get confused as to which boxes had been through the "trash run". As I emptied boxes, since I was putting stuff in Trash and therefore the total box count was going down, I flattened and stacked them.
- Repeat for each box until each box has been through this phase.
So far, it may seem like a tremendous waste of time. You've boxed everything once, and then you've boxed everything you're keeping, _twice_, and the keepers are not one whit more organized than they were one you started. But the advantages, to me, are: (1) there's very little thought involved; the stuff can be boxed ReallyReallyFast, (2) the boxes are neat tidy modest-sized units of junk, and I can focus on one box at a time, (3) identical stacked boxes take up less space than miscellaneous stuff, (4) the trash-and-not-trash step makes me focus heavily on what I'm just plain getting rid of, without distracting myself with other issues, so the sheer trash gets out of the house pretty early. Another advantage for you is, (5) the boxes can be hauled upstairs, so that you don't have to work in the basement and (6) a clean wall of identical boxes should, I think, be much less overwhelming.
At this point, you can do a bunch of things. If a big percentage of the stuff is from your parents and you want to warn them to take it or lose it, you could do a run through the boxes extracting your parents' stuff. The same is true for any other category that forms a large percentage of the stuff.
Or, rather than doing whole rounds through the boxes, you could just focus on one box at a time, dispositioning each item in it before you move on to the next box. Or you could try a variety of approaches.