I've been tinting for ten years... My personal choice for your situation would be 20% on the back, to look OEM. then 35% on the front. why? becuase the 50%, while legal, is too light in my opinion. the 20% is too dark when your state law says you need 50%. i'd go 35% and take my chances if i were you. otherwise, stick with what's legal, i don't know how much the fine in MN is, but in WI its $180. i got it twice in my lexus. i think 35% still looks the best though on the fronts.
However, if you get a good tint, the benefits (heat & UV Protection) will be nearly the same between the 50% and 20%, so if your going for heat/UV protection, won't really matter what you put on. if you're going for looks, it's completely up to you. i just feel 20% on the fronts is too dark. and yes, my eyesight is perfect 20/10
as for eyebrow... 20% is what i prefer. the 5% is a bit dark and looks goofy in my opinion. and 35% too light.
all that being said... i have kept to legal limits after getting the fine twice. the GFs mercedes & focus are both legal (50%f/35%r) my STi was legal, and now the jeep has 50% on the front per the GFs request, since she'll be driving it more this winter, and she works at the cop-shop!!! otherwise, i was going to go back to 35% on the jeep for sure, but not with her working right there.
to summarize...
20% back
35% front
20% visor
and make sure you get a good 2ply metallic or hybrid film. NOT a dyed-only film.