If there is a technique for cover folding I never found it.
My Golf has been covered for eight years. Overall a positive experience, but certain joins on the cover abrade the lacquer, leaving fine scratches. They cut back OK but over time leave a slight imperfection.
This winter, maybe due to lockdown, I got microblistering on the A posts. And a patch of milkyness on one panel. After a week uncovered, the blisters and milkyness vanished.
So care is needed if you use a cover long term