I altered the default game FOV to 85 in the falloutprefs.ini in My Games folder. When I restarted the game, the FOV had defaulted to the default one. What is the best way to make this adjustment so that it "sticks"?

If you have the game for steam there is a Fallout_default.ini folder in the New Vegas directory, this file will reset changes to the other .ini folders, you need to change the fov there or it will be reset. you can also change the fov with the setcamerafov (insert desired fov here) you open the console with the tilde key ` but using the console will disable any acheivments.