Call them when you return or if you are delayed so they don't worry. Many towns do not have gas stations. If you're not accustomed to the desert, be sure to drink a lot of water or Gatorade-like beverage to avoid dehyration. For trips over two hours, consider bringing lunch or a snack. Never cross a wash when it is flooded.
High altitudes are colder than low altitudes.
Bring appropriate clothing for your destination. If you want some good, solid advice about backcountry hiking and exploration, be sure to read the Vulture Peak Rescue story, especially the two letters appended to the end. That's good advice for traveling in the desert.