Here are just a few suggestions :
1. Make sure heating system gets serviced including hot water heater and pipes are properly insulated.
2. Make sure that windows are working properly and that the seals are not broken.
3. Make sure that any place air comes in gets sealed. You can buy winterizing supplies in Home Depot for very cheap money
4. Make sure you have an extra space heater around in case system fails and also have candles and blankets ready in case power goes out.
5. Lastly keep important phone numbers handy for management company, plumbers, electricians, city hall in case all the above fails.