How can I prepare for a career working for a cryonics organization ?
This depends upon what you want to do for cryonics. If you want to do accounting for a cryonics organization, then study accounting. If you want to do research to help advance the science, then study chemistry and physiology to empower you to improve perfusion methods and reduce cryoprotectant toxicity. Training to be a perfusionist would provided you with skills greatly in demand by cryonics organizations. A medical degree would be the excellent, because cryonics organizations can greatly benefit from help by physicians (especially specialists in emergency medicine). And if you lose interest in cryonics, you still have your medical degree. Cryonics organizations are small, so they do not have a large staff, but if you are well-trained and enthusiastic your chances of getting a position are not bad.