Oh, something I have been doing for so many years I almost forgot to mention it:

Anything that gets mounted to my handlebars gets a couple layers of cloth tape wrapped around the handlebar under the mount. This gives the mount something to bite into that has an adhesive back.

Any kind of cloth first-aid tape seems to work very well. It doesn't take much.

Another thing that works well is to replace the hard, slick, plastic shims that come with most product's mounts with a shim cut from an old inner tube. The rubber inner tube material is much softer and less slick allowing for a much better grip on the mounting surface.