1. Some Photoshop experience would help out greatly.
2. Watch these videos on youtube.
http://youtu.be/0pvujv0Uxs0 http://youtu.be/t3muMJlCoOA http://youtu.be/UM90f2T-cF8 http://youtu.be/nxrmrza34pg http://youtu.be/jS6LaCXExHM. I also watched ones for PES and FIFA, search PES facemaking.
2.1 This tut is teaches you how to use the first two tools below
viewtopic.php?f=144&t=830283. You need these tools that can be found here.
3.1 NBA 2K12 Decompresser (decompresses the .iff files)
3.2 NBA 2K12 Cyber Face textures (exports and imports the decompressed .iff and .dds files)
3.3 Photoshop DDS plugin (You can't edit the .dds files with out it) find this plugin on the Nvida website or google it.
3.4 For 3d editing you would need Python and Blender
3.5 NBA 2KX Mod Tool
Tools in 3.3 amd 3.4 can be found here
viewtopic.php?f=144&t=83317 , but i would not worry about those until you have learned the basics of cyberface editing and using the tools (3.1 and 3.2).
4. Key photoshop tools you will need to know already or learn to use them.
4.0 Opactity
4.1 Pen tool
4.2 Eraser tool and Opacity settings
4.3 Color Balance
4.4 Hue/Saturation
4.5 Brightness/Contrast
4.6 Levels
4.7 Curves
4.8 Exposure
4.9 Vibrance
4.10 Free Transform, Warp and Perspective
4.11 Layer Masks
Also Color Match, Blur tool, Sharpen tool, Dodge tool, Burn tool, lasso tool and the Clone stamp tool.
5. Sources of high quality photos
5.1 ESPN - you will need to use some sort of program or web tool to rip the pictures, as you can't right click and save picture on espn.
5.2 Google
5.3 Youtube videos at 720p or 1080
5.4 Yahoo
5.5 zimbio.com also has good photos for lots of players.
The rest you have to just watch videos and ask questions around the forums in the patching help section, the tutorials section has lots of useful info also.