i havn't had much trouble with my neck like this. though with the ol' cartridge razors i would get terrible razor burn on my neck but since goign straight that has all been a thing of the past.

i simply lift my chin up, that tightens up the skin on my neck.. then i do N-S pass and then a S-N pass if needed. also due to holding the razor it is easy to slightly angle the motion from outside in if your hair grows that way.

i use my right hand to shave the right side of my neck and left for left. that above movement of left hand, right side with right hand pulling left seems so cross eyed and crooked with a N-S pass, i'd be scared to try it.

~J