You have quite the task ahead of you!
However, this is a very supportive group so you've come to the right place.
I'm assuming that if you are posting pictures and descriptions for all to see, you are open to feedback/criticism/suggestions and the like.
I'm no expert at organization, but here are some tips that *may* help:
1. Trash the cardboard boxes. I know it's tempting to keep them around just in case you move or need to store stuff, but cardboard boxes will always come around when you need them, plus, the more empty boxes you have around, the more tempting it is to fill them up with stuff.
2. Wood is good, but have an idea for it. If you are not going to use that banister in the next few months, ditch it. Same goes for the rest of the wood. Any wood that you have a real intention for (such as building cabinets), would be definitely good to keep.
3. Ditch any paint/varnish with less that 1/3 can left.
4. Get rid of 'made in China' and cheap stuff first and keep 'made in USA' and the good stuff. This could be a great starting spot. Heck, if that was what you held your criteria to, it would probably be a lot easier than you think to clean out a shop. This is totally personal opinion, but I would ditch anything made in China way faster than anything in the US of A. Keep the metal tool, ditch the cheap plastic one. Keep the nice wood, ditch the pressboard...that kinda thing.
5. Come up with a fun theme! This is just food for thought. I have found it is MUCH easier to work within a space if I have a theme going. My theme is 1950s, and more specifically, Craftsman tools. That means its MUCH easier for me to either get rid of or not even consider something if it doesn't fit within the 'theme'. You can be creative here and it makes the garage work so much more fun.
Please, please take all the above with a huge grain of salt - you've got to make things fit for you. You've got a great task ahead of you but it sounds like you have great motivation as well. Thanks for posting what you have...now we can keep you accountable!!!
Remember, nothing's going to change unless you get serious. Start cranking it out!! When in doubt, throw away or sell/donate.
Oh, and we'll all be waiting for updated photos in a week showing a cleaned out space