There are lots of ways to get the job done and each boat may be different. I follow my Mercruiser repair manual for layup. Basically, they have you add fuel stabilizer, warm the engine and change the oil and filter. Then run the engine on the new oil until warm then fog the engine. Remove the spark plugs and fog the cylinders. Drain the engine block, exhaust headers, and power steering oil cooler. Close the drains and remove the thermostat. Fill the engine and exhaust headers (remove the hoses monetarily) with non-toxic antifreeze. Replace the thermostat with a new gasket. Check or change the gear lube in the lower unit. I have used this procedure the last couple of years without any problems. I really like seeing that the engine is full of antifreeze. The book describes all of this in more detail and if you are going to do your own maintenance it's really worth the money. Now I am ready to do mine.