The procedures described here are for volunteer laypeople. You, as a layperson, may not wish to get involved at all, but even a little assistance can improve the quality for the patient. Existing professionals such as doctors, nurses, or funeral directors may perform many or most of these tasks at your request, but they will frequently need prompting because they will be uncertain what needs to be done. You will need to be very assertive.
The procedures for trained Oregon Cryonics staff are very different and can be found at Manual - Stabilization.
Move the body onto a wheeled stretcher. Place the head in a Cephalic Ice Bath. Add only ice. Do not add water, or it will be messy during transporation. Cut free any clothing near the neck. Ice on the body is optional. Try to get at least one bag of ice on the upper chest and neck. Make sure it's double bagged and has absorbent to prevent water from dripping.
Try to obtain heparin ahead of time. It will have to be administered after pronouncement, and administration will required access to a vein. Try to convince the medical staff to leave an IV line in place in order to allow administration of the heparin. Flush with saline, and perform manual chest compressions for about five minutes in order to help distribute the heparin.
Transport to a suitable facility.