It can be blown out with the bike pump attached to the heat exchanger and let the water out of the risers via the stop-cock. That's all you have to do. BUT we usually run anitfreeze through the system just to be safe.
Other items that are important are the oil changes BEFORE you put her away fogging the block and cylinders. That may take a pro unless you have your own can, mix, and take off the fuel hose before the filter.