Navigation is one of the most power-intensive apps, so keep your phone plugged into a high-quality car charger, especially if you're streaming music and/or using Bluetooth (also power-intensive features).
Tell your phone to provide directions to a destination:
Get directions from anywhere to your home or work addresses with one touch by setting up a task shortcut for the Maps app:
When you're ready to roll, just touch the shortcut, and your phone will talk you through the directions.