My neck was a surprise for me. I had done the sideburns and cheeks and was worried about the neck. I found stretching really made a difference. Doesn't matter as much on the cheek, jaw, sideburns, or face in general. I do stretch there but it did not make near as much difference. However, on the neck, stretching really made a difference. I point my chin up toward the ceiling to get some of the stretch and with my second hand pull down on the skin for the remainder. This is for a north to south pass. I do use my right hand only and had to find a way to both hold and point the razor to do this. In both situations I 'point' the blade toward the back of my neck and pull downward.
For the upward pass I found holding the blade almost parallel to the skin worked quite well and this was the surprise. I assumed I needed a greater angle but this one worked great. The spine is maybe the width of a nickel off my skin for this pass. I also have found a scything action adds to the ability to 'get more hair'. I think the scything action also helps with the hair that grows in several directions.

Happy shaves