Some good advice there guys
I have the same trouble with the neck, my beard grows out from windpipe to ear, and after months of trying I still find if I am gonna get a rash or leave stubble,thats the spot it will be.
Jockeys videos are very good IMHO, the diagonal from above and below helps a lot, remember very little pressure and keep the blade angle low, just go very steady using short gentle strokes.
Also what I found works is to use short scything motions to cover the area, kinda like windsheild wipers.
TOP TIP: after starting on your cheek, stretching and working downwards, grab another stretch and you will find you now have a fresh bit to shave right on your jawline, or maybe even a little above, shave that still going straight down, then grab another stretch, if you have a full face dont be surprised if your eye on that side is now closed because of the skin you are pulling up, anyway that will give you another fresh area to go at, once you cant pull any more skin up to shave let go and you will be surprised how far down the neck you have just gone, and because you shaved it with super tight skin it will be a quite close shave too, leaving less stubble to have to go at to finish the job, using the diagonal windshield wiper technique.
Hope that all makes sense, and you find it a help
Best wishes Ralfy