At almost 50 I'm starting to classify as an old fart with baggy skin.

I find actually pulling down on the skin on the very top of my CHEST work well to get the skin taught. I do WTG and ATG on my neck, in fact when I do ATG it's normally ONLY on my neck for just this reason. In fact, to be precise, because my hair also grows E to W (or W to E) on my neck, the WTG and ATG on my neck is really two XTG passes.

I shave with a DE on Saturdays, and with that I can go sideways. I find that sideways DE shave once a week is enough to keep most of the problems at bay.