I've been thinking about doing the same thing. Do you have any advice before I start?
When I started in high school 20 years ago, it was just a tree of everyone I knew I was related to. Then you get back far enough and have to ask people for help. My grandmother remembered dozens of names and dates, which got me further. Ancestry and similar free websites (findagrave.com) can fill in a lot. Newspapers.com helped me find a ton of obituaries and gossip column entries, which filled in even more.
It's only recently that I got into thinking about the "History" going on around my ancestors when they were alive, and that's been driving my interest for the last year. Person A lived in this place in the 1890s--what was going on there, and how were global events affecting them? Newspapers.com or another archive were very useful for this as well.
Although Ancestry and Newspapers.com are subscription, even one month lets you dig into and download as much as you want, so if money is tighter you can sign up for a single month and dedicate a lot of time to getting as much raw material as possible.
What software tools did you use to organize your archive?
How did you add the metadata?
Get Info in Photos and add all the metadata you need.
For myself I try to set the date for the photo — at least get close to the correct year. I set the day/month/time to something like January 1, 12:00 AM as a sort of indication that I have no idea when during the year. And if I am not even sure about the year I indicate as much in the description for the photo.
I enter a description (on export this will populate either one of the EXIF or IPTC properties or both). I describe what was written on the back and/or front (if any). Describe who I think the photo is of, maybe where the photo came from, etc.
I add keywords. Keywords for each person I recognize in the photo, keywords for the collection the photo came from, keyword "Family Photo" so I can differentiate from all other photos in my library.....
Any decent photo editing app should have a means to set the date, enter a description, add keywords. And all of these are exportable — are part of the EXIF and/or IPTC spec. And, again, a decent photo editing app will preserve these on export.
The beauty of course is that you can then create "smart albums" to show your family photos chronologically where: keyword = "Family Photo", sort by date. Or find all photos of "Faye Coble".
All my resources are kept in a single directory, with subfolders generally using "lastname, firstname m" naming. I don't do as much cross-referencing (shortcutting) as I should, but that's also handled to some degree in the GEDCOM and full-text search of the filesystem.