Hi I'm a new refugee from Ubuntu. I am putting this post up for others as an example of a method that works.
Things I tried before that didn't work:
From a fresh install, I went to the device manager and selected the nvidia driver. It prompted me to reboot and broke my system, dropping me to the shell on reboot. Very disappointing and convinced me off the bat that LMDE is not ready for mainstream. Normal people will not put in days of troubleshooting to get such basic functionality to work. From the error messages, the problem seemed to be that the nouveau drivers did not unload despite being blacklisted. I tried a bunch of different methods off the forum here and blogs that didn't work either.
Things that worked:
I used the "simple graphical installer" script found at http://smxi.org/ and it magically made everything work! This script may be known among debian veterans, but as a new person I was completely unaware of it until I came across it several days into troubleshooting. I strongly suggest this be included with the default LMDE install or at least included in some troubleshooting documentation somewhere.
I would suggest people who haven't gotten their nvidia gfx drivers to work yet try out this script. It worked for me.