The USGS Quads are also very valuable resources to have with you. The important stuff to bring Water Water is essential in this state. At the lower altitudes, you'll be hiking in the desert, where the temperature warrants a good supply of water. At altitude, where you may not be hot, you still need water, because your body needs more fluids at altitude. First Aid Kit Don't forget a good basic first aid kit, with any luck you'll never need it, but bring it anyway.
Some people feel hiking boots are unnecessary for most hikes.
Regardless, wear boots when hiking in the desert, if for nothing else than to protect your feet from rocks, cactuses and various critters that might want to snack on you toes. A Friend Try not to hike alone, especially in the more remote areas of the state. Chances are you won't see anyone all day, and if you do something as simple as fall and break your ankle, your going to be in for a bad day. Unless you are very familiar with the area to be hiked, bring a good map and a compass, and know how to use both. See TopoZone for online topo maps.