• Use text messaging whenever possible. Text messaging typically uses less power than regular voice calls. Cell towers are also often overwhelmed with voice calls during disasters like hurricanes, so using text messaging is a more reliable option altogether.
• Turn off features like GPS and WiFi. While these features are helpful during normal circumstances, they can drain your battery during a power outage. Chances are if you don't have power, you won't have WiFi, so having your phone constantly looking for hotspots will drain your battery quicker. After conditions return to normal, remember to turn WiFi back on.
• The next step may seem obvious, but is often forgotten. Make sure you fully charge the battery before the storm. Also, use your car charger after the storm to re-charge during any power outage. Car charges typically draw very little amperage so you shouldn't have to worry about drawing down your vehicles battery if not used for a few days.
Stay safe and if you plan on evacuating don't forget important data on your computer(s). While the storage media can be replaced, the data cannot. Now would be a great opportunity to backup your data to the cloud or make some other arrangements before it is too late.