The easiest solution would be to make two maps out of this. However, it may be possible, with a lot of tinkering to get all these different areas to look better.
The first thing would be to take away the dark green outline for the rural reserve. Second, if the number of outline colors/widths can be further reduced, definitely consider it. For example, are the census tract boundaries really important? If not, the white lines could be discarded so that we can focus mainly on the tan, green, and blue areas (without any borders because the area color change is sufficient).
The outline color for the future consideration districts might be the same or similar color to the highway lines, but I'm not sure. Maybe the highways could be eliminated?
Some other ideas might be to integrate the legend and the title a bit more by not having them in boxes - or, if the boxes are kept - taking off the outlines. I'm not sure on that but you could try it. There may be something that can be done with the UGA versus district boundaries so they aren't competing. Maybe make the UGA a bright yellow and put it on top of the district boundaries? You could make the whole thing really bold by darkening the land use colors significantly and then using bright/white/yellow colors for outlines.
If it were me I'd just toy around with all these things until the most important info really pops. I was just making a collection of National Geographic maps that I cut out of old magazines and pasted on black paper and what I'm noticing from them is that the ones that are in-line with the articles only show a few variables at a time on top of a very light reference geography. I'm not saying to do that exactly, just that perhaps looking at some inspiration pieces might help for you too!
Anyway, your map is a good start!