I have 'necklected' neck exercises so far, and would like to change that. What are some exercises for a strong neck? Is a one of those head harness necessary? The only device I have and use regularly is a kettlebell. I don't want it to be bulky, or strong enough for martial arts, I just want toned muscles.
In my opinion, those head straps look kinda dorky. but you could try it, if you don't want to buy one you could always make one with a small plate, rope and a headband or vest tied around your head etc. Maybe you could use resistance bands somehow?
Generally stretches and mobilty work will do wonders, things like Neck rotation, extension/flexion, chin tuck. Head lift/crunch
Also Mike Tyson famously had a huge neck and trained it with exercises like the neck roll/neck bridge, but if you attempt this please be VERY careful and maintain strict form as you can seriously injure yourself.
Making sure you hit traps well on back day is very important as it will help support the back of your neck and keep your spine protected.