Longtime Cloudflare user. This isn't specific to Cloudflare, but common sense would be to always have a backup. For example, my sites I've got Cloudflare in front, but in the background I'm caching all my content and pushing to BunnyCDN, so if I need to fallover, I can safely fallover out of the network into a live cache (each request I re-populate cache in background job).

It's saved me lots of time and energy.