Real quick sketch.
I don't ****ing get necks.
GEEEEIST
My advice would be to toss up a mirror and try to do it from memory based on what you see. Necks took me a while, and can still give me trouble. The biggest thing when trying to make multiple characters is remember different body types and such, so you can't always have the same neck.
Stick with ONE character, and draw them over, and over, and over, AND OVER until you have them DOWN. Then move on to a different. This is what I did with a character I WAS gonna have for a story/comic. Never got anywhere.
Feel free to ignore me, my head is killing me, I'm home from work due to doctors orders because of chest pains, and butterflies.