You bet there are steps to take. The reference to A. Highlfield is worth considering. Also see what the California Turtle & Tortoise club says.
Cover the basics, have well fed and well hydrated animals in a secure and dry but some humidity environment. They must be empty of ingested food. Well insulated from both excess cold and heat and protected from rodents, auto exhaust or noxious fumes, and you should do fine. Do the basics and they will emerge healthy and randy and ravenous in spring. Neglect the basic requirements and they may emerge sick or not at all... Good luck and give it some thought to find the best place and provide what they need. Don't hesitate to check on them, or even offer a cool soak. If set up properly and using good common sense, this will be relatively care free and "natural process". Vic H. Imperial Valley, Ca.