Aside from getting the equipment necessary, planning the trip there is the getting in condition. One item that very few hikers take on the trail and I consider the best piece of equipment available for a long hike in the wilderness is a GPS. This piece of technology and a map will prevent me from getting lost. The draw backs are it's relatively heavy at about a pound. Battery use is high, about 4 batteries (aa size) every 24 hours of usage. Advantages are you always know where you are within 50 feet.

Maps, Topographic 24,000 scale, a little work here is required as I line them along the 1000 meter lines. This makes it much easier to plot and find your position. Most GPS allow you to display either Latitude/Long or UTM Grid. You will find the Lat/Long lines on the Topographic maps to be a little wide for any real accuracy.

Also required is a good water filter, Trail wisdom says that in the US you should be OK with just a filter and a purifier is not required (a purifier uses chemicals such as iodine to kill additional micro-organisms. I chose the Pur Hiker Filter, Four things drove the decision:

Although a filter should be enough, I will probably use a purifier filter for the first part of the trail, The water from any natural sources lie on routes that may be used by Illegal Aliens or Drug smugglers, Surprisingly they are both groups that are not known for their ecological awareness.