In my experience there is no one best way to work holding.! You just use which ever method gets the job done easiest.?. . . I'd use Chewing gum if it did the job.

Vacuum is ok if you have plenty of it and it suits the job, Often it doesn't if holes or cut thru. I've got some really expensive hold down clamps for alumiium and I've also got some home brew holding devices made to suit jobs at the time and I can tell you the most used by far is the home brew stuff.

I've also got a big box of screws and large rolls of double sided carpet tape and these are often used for holding wood or thin material.! . . . . . Can't beat double sided carpet tape for large thin material. In the past I've used DST while Engraving large and expensive piece of Brass on my machine which vertical mounted and it didn't move fraction of a millimeter.

Often I'll use DST and screws/clamps.? If part doesn't have thru holes or can't be clamped and I don't want tabs then I'll use DST so it doesn't move or get pulled back into cutter when outer profile is finished. I'll use the screws or clamps for holding waste material and keeping secure and flat to table while job runs.