Hello (potential) cryonics customer, you should ask for third-party audit of your cryopreservation. This ensures that the cryonics providers aren't performing the procedure badly, say through negligence, ignorance, or something else.
Specifically, you should ask that the following be sent to an imaging specialist of your choice AFTER your brain has been preserved
- An x-ray of your preserved brain, and
- A needle biopsy of a few brain areas (say, the frontal cortex, parietal cortex, brain stem, basal ganglia, and thalamus)
The x-ray will roughly show if large parts of your brain were not preserved well. Micrographs of the biopsy samples will show in fine detail (tens of nanometers resolution) the quality of your preservation.
This information will give your loved ones peace of mind that you've maxed your chances of revival and it will also give other cryonics customers confidence that your cryoprovider is worth paying money to.
These auditing requirements come from a video by the Brain Preservation Foundation (BPF), Preservation Done Right, and from their article, Vitrifying the Connectomic Self (p. 5, 2nd para).
Disclaimer: I volunteer for the BPF, and am an ex-Alcor member.