Hey. Like the mentioned exercise above, using your neck over hanging on a bench with a friend; back extensions are good are for you as well. This is because you will should feel the burn right up through your traps and up into the base of your neck, if you do enough (with good posture).
Speaking of posture, if the biggest thing you are worried about are the aesthetics of the way a long looks, good posture will do wonders even for the longest of necks. So, make sure you don't have what is called "forward head posture". Look it up. If you do, there are many exercises available online to correct this type of bad posture.
Be careful of any weighted exercises for your neck. If you start to have any head aches, stop, hydrate and take it slowly for the rest of your sets.
At the end of the day the hardest thing with these exercises are keeping to them, they might not be as glamorous as bicep curls but **** what it looks like and you'll be better for it in the long run.
have a good one champ.