Questions about steam boiler startup

Thad English

Once it cools off I want to be ready to fire up the boiler but I want to make sure that I don't do anything in the wrong order and damage it. I drained the returns in May but left the water in the boiler. Then I flipped the switch to 'off' and let the whole thing cool down. No gas usage at all since then. Once it starts getting cool out do I open the valve and let the boiler water back into the returns and then fill the system back to its normal water line? Then do I flip the switch to turn the gas back on and let'er rip? Or should I drain the boiler too and then fill the whole system with fresh water? I want to do it right so any suggestions would be much appreciated.