Usually to prove my point that anyone can organize, I'll ask for the self-proclaimed least organized person to sort a bin of select items.
Never have I encountered someone who couldn't sort this bin into piles of the same types.
We were all trained to see patterns as we learned our colors, shapes, and letters.
Now, if I've convinced you that you are capable - I have to give you the "rules". Most people who set out to get organized and fail do so because they didn't have these points in mind beforehand.

THE RULES

1. Set aside the time.
Sorting will take more time than you think, and will make the mess larger and more spread out. If you don't take the time, you'll give up mid-way and stash. Then you'll be left with a big mess, no sense of accomplishment, and no progress. I have a few friends who subscribe to the "only clean fifteen minutes a day" philosophy. But as another old friend said, "That's only enough time to shred the junk mail."
It can take anywhere from six to eight hours to complete a basement, garage, or large room.
So start small, and take the time.

2. Bring with you: storage bags, pen and paper, a donation box, and a trash can.
You will need the bags for small items, pen & paper for notes or labels, the box for things that will obviously be donated, and there will be trash.

3. NO SIDE TRIPS
If it belongs in another room-make a pile of things that belong in other rooms.

4. Disconnect from the objects you are sorting - no reminiscing.
When we start to reminisce, we stop sorting, and start planning. There will be plenty of time for reminiscing during the purge phase. So for now, no thinking, just make piles.

5. Don't skip anything.
Chances are that box in the corner is filled with as many disjointed items as the rest of the room. And knowing what you have is half the battle.

6. Contain it.
If the task becomes too overwhelming, don't lose your progress - put your piles into containers .