Hi, I am actually thinking about taking on a small project, well kinda big for me because this is the first I've ever thought of taking on. I am thinking of taking the mask of the Nightingale helm (basically keeping the mask but getting rid of the hood), and maybe retexturing it. But lets take this in baby steps.

How would i go about separating the mask from the hood? What program would i need? Are there any good tutorials for it?

It could have been so easy if the cowl and the mask were separate pieces, but it looks like it's all one.
You'll need a 3D modeling program like http://oblivion.nexusmods.com/mods/12248 (free) or 3DS. Once you learn the basics of navigating in the program you'll basically just be removing vertices you don't want.

Personally I use Blender, but since it does not yet import/export Skyrim nifs I found http://wiki.tesnexus.com/index.php/Creating_an_armour_for_Skyrim._Part_1 explains a work around very well of how to manipulate the mesh before and after to get it working. Because you'll be working with a rigged mesh, expect a steep learning curve.