Does anyone have a good method for turning a bandanna into a neck drape?

What do you mean by the phrase "neck drape"?

If you are referring to those little gizmos that contain hygroscopic crystals and that tie or drape around your neck (usually), I have usually wet the bandanna and simply arranged it around my neck. This works quite well in hot, dry conditions - not so well in high humidity.

Rewet if possible. What works equally well is to saturate a full brimmed cotton hat (so called boonie type) and slap in on your head. Also makes sense to wet your shirt and put it on wet. Particularly if there is a breeze you will get nice and cool.

I have seen neck drapes that hang down from hats to block sun.

1. remove hat.
2. wet bandana
3. place bandana on head
4. adjust bandana to desired length.
5. reinstall hat.

have seen hikers, construction workers, landscapers and backwoods rangers use this approach. it seems to work for them.

good example but is not me
or
this one, side view regular bandana