Sorry I didn't notice your question until now.
I changed the system fonts to Lucida Grande with the Schreiberstein Solution:
https://github.com/schreiberstein/lucidagrandeyosemite
I stopped using Safari, which appears to be hardwired, switched to FireFox and installed therein:
No Squint;
Theme Font Size Changer; and
Roomy Bookmarks Toolbar
I increased the minimum display fonts in Apple Mail from within the program
I used TinkerTool to try to universally change the minimum fonts and sizes within all other programs which allow default font and size changes, keeping in mind that TinkerTool does not override any program's prohibitions but just gives you a way to change all the rest in one step instead of app by app
I turned on Dark Menus to create more contrast between active and inactive commands in the dropdown menus.
Regards, Nate 😀
PS I went to System Prefs/General and changed Appearance to Graphite, SideBar Icon Size to Large (because it enlarges the sidebar fonts too-don't care about the icons); Default Web Browser to FireFox; and unchecked LCD Font Smoothing;
I went to SysPref/Accessibility/Display and checked Increase Contrast and Enlarge Cursor Size;
I kept SysPref/Display/Resolution as Best for Display not scaled; and Brightness to Automatically Adjust
and probably a few other things I probably don't remember right now.
All of the experimenting and turning things on and off was **** but I hope this helps others.