Strengthening your neck will benefit your posture and the overall look of your physique. But not many people do any sort of direct neck training. Sometimes it's just a time issue. Here's an exercise that gets the job done quickly: banded bent-over neck extensions.
You'll need a light to moderate band, an unweighted barbell set up in a rack just below knee height, and a bar bad.
Stay strict with the slow negatives and let the bar pad stretch your neck at the bottom of the movement. Be careful not to overextend when you're in full extension. Get a 1 second squeeze at the top and use the barbell to support your body enough to keep your spine relatively neutral.
Do 4 sets of 8-10 reps at a 5101 tempo. However, if this is your first time directly targeting your neck, I'd be modest with the volume and stick to only 3 sets. You're going to be sore!