Originally posted by: Dabappa
A 4 way neck machine is probably the best way.
Something like this:
Link
If you go this route be sure get some instruction/supervision and start very light.
The gym I go to used to have one but got rid of it for liability reasons. The big guys (which I am not) all compained when it was gone.
I managed to add a 1/2 inch to my neck size in the 6 months or so that I used it.
Shoulder and upper back lifting will help, but it is really not the same, and even the trainers admit that there is no other equipment that will substitute.
Wrestlers and ground fighters do some body weight stuff, like bridging, but it looks incredibly difficult, dangerous, and uncomfortable.
Good Luck,