Most people choose to be decapitated before being sent to a cryonics center. I personally think it's all bunk. The damage the brain receives from being frozen is extensive and basically destroys everything that's there. I don't expect people from the future to ever be able to recover a hard drive that I've sanded clean either.
The current technology favored by Alcor is vitrification, not freezing. Vitrification is an ice-free process in which more than 60% of the water inside cells is replaced with protective chemicals. This completely prevents freezing during deep cooling. Instead of freezing, molecules just move slower and slower until all chemistry stops at the glass transition temperature (approximately -124°C). Unlike freezing, there is no ice formation or ice damage in vitrified tissue. Blood vessels have been reversibly vitrified, and a whole kidney has been recovered and successfully transplanted with long-term survival after vitrification at a temperature of -135°C.