First of all, always listen to your body and if something hurts, stop! You can do most exercises with your neck on the ground until you start to build the neck muscles more. Even when you do have stronger neck muscles however, there are going to be days your neck is more tense than others and you need to take it easier than other days. Don’t push through too much neck pain.
Try not to look at the ceiling or sky when you lift your head up and try looking towards your navel or thighs instead. Your neck can also take on more of the strain if your core if feeling fatigued, so feel free to take a little break. Perfecting the neutral spine can help with neck tension as well.
Here are some short videos that focus on alignment and can help with neck strain:
This class is great if you want to be gentle on your neck, it provides a lot of modifications and props to help support your neck: Easy on the Neck