Jaw/Bite work, such as holding a weight in your mouth, chin push ups/forward, biting a towel and pulling, and tongue exercises.
Direct neck work; curls, extension, twist. Can hold a weight in your mouth here too. Wrestler bridge on the neck, rolling around. Just feel your neck do the work by doing it for time. 20 minutes of neck work is good. 30 minutes when your neck is a bit stronger or you're up for it. Don't do no pussy resistance, actually try to get your neck stronger even if you're doing that shit for a long amount of time. Just going through the motions doesn't get you THAT neck, but it'll get you half-way there. In that same amount of time, if you put your heart into it, you'll get the neck you want rather than half the neck you want.