build the best reference image

not to start a flamewar (yes, I've read a few other posts)

but.. what's the best way to build a reference image.. 

I've trawled the standard sites but am still trying to find a good walkthrough..

is it mdt? 2013?

is it sccm only? 

It's been soooo long since I worked with MDT.. cannot even remember it properly.. 

and I haven't ever made a reference image in SCCM... we had people doing that for us.. but now.. I wanna do it. if for nothing else then just to learn how (again!?)..

links or ideas etc. are appreciated..!

Kindest regards, Martin