Anyways, get your gear together. When possible, use light gear -- it is easier to hike when you are carrying less weight. But do not be lured into using gear that you are not comfortable using. Backpacking can take you to remote places where evacuation can be difficult, don't put yourself into an unsafe situation.
Hopefully by now you've got some maps. At this point it is appropriate to freak out a little bit. Your maps alone probably weigh about five pounds! You won't be familiar with the layout and flow of the maps and you may even have trouble reading them. Here's a hint. It doesn't matter. You'll be reading them one at a time. Go ahead and leaf through them, pour over them if you want. It doesn't matter.
What does matter, is that you don't decide you're going to carry five pounds of maps at one time. So, what do you do? You need to mail these maps to yourself at strategic points throughout the trail. And by strategic, I really do mean arbitrary. Any place is as good as another, as long as you are relatively certain you will be going there. The CDT has a billion alternatives and the trail is constantly re-routed, such that nobody really knows where it is on a day-to-day basis nor does anyone agree on mileage. So, here's what I did. I looked at my maps and said, "man, these are heavy, I don't want to carry more than a sixth of this at one single moment." Then I looked at my wall map where I very well can't accurately judge mileage between two locations, it doesn't matter, and picked six locations the are spaced "equidistant" from each other. Ta-da! I had a resupply strategy.
Next, I consulted a combinations of Yogi's Guide (http://pcthandbook.com/) and the internet to be sure that none of my "strategically" placed resupply locations were not on any alternates. I haven't decided which alternates I will and won't take. Therefor, the simplest way to manage that and maintain my flexibility, is not to mail anything anywhere that I'm not certain I will be. If one town happened to be on an alternate, I simply moved either north or south to the nearest town that was not.
Next, consider any terrain or weather based issues. In the case of the Continental Divide Trail, the major weather related concern is crossing the San Juan Mountains in southern Colorado. At this point in the hike the trail climbs to high elevations where snow will inevitably still lie. Therefore, cold weather gear and even an ice axe may be necessary. So, make sure one of your mail drops goes to a location just prior to hitting this section of trail. Make that a mail drop as well.
Then, consider the following issue. Are there any places where I cannot get any sort of food and cannot bypass? In the case of the CDT, I determined there were a couple, as in two. I'm not a picky resupplier. I've resupplied from convenience stores before, and while it isn't a great option, it can and will work. On the other hand, I don't care for planning, enjoy flexibility, and know for a fact that you can always hitch-hike your way further down the road to a better place if need be. Regardless, sometimes it is easier to just suck it up and send yourself some food rather than waste a day figuring out where to get it. In the case of the CDT, both of these locations are relatively early in the hike and so I will be packaging and possibly even mailing both of these before I even leave town to begin my hike. (On the Pacific Crest Trail these locations were later in the hike and I simply shopped on trail, mailed them from my current town to the next one, and had food waiting for me at the next destination.) Now, either add these necessary resupply places to your list of mail drops or, if one happens to be near one of your "strategically" chosen locations use the location where food is a necessity to minimize the amount of packages you will need to collect.
Now you can split your maps up into appropriate groups. Pick 'em up. Have a good long sigh of relief and a nice ol' smile. That heavy stack of maps is nothing now. Look online or at Yogi's Guide to find appropriate postal codes or local businesses willing to hold your packages. Here's a hint. All U.S. Postal Offices will take packages addressed with simply your name, the town name and state, and a zip code. Then write "HOLD FOR THRU-HIKER" on the side of it and an estimated time of arrival and they will hold it at the post office for you. However, post offices aren't open at night or on Sundays, therefor, if their is a local business of some sort willing to hold your package, this address may be an easier option for you.
Package these up and address them. I never seal my packages so that if I decide I need something last minute it will be easy to add. Then, leave them with a reliable person with the appropriate money to pay for each package to be sent. In my case, I'm leaving mine with my roommate Jeff. (Thanks Jeff!) As I hike I'll know when I'm nearing a town that I've designated as a resupply point, I'll call Jeff, and all he will need to do is seal the package and drop it at the post office.
So, you've got maps. You've got gear. You've got a basic resupply strategy.
That's about it. That's about all you need to do. Sure, you need to figure out how you're getting to the start of your chosen adventure -- but that's relatively easy. Also, in the case of the Continental Divide Trail special consideration must be given to the water situation in southern New Mexico. As in, there isn't very much of it. How are you going to handle this? You may need to cache some water for yourself in the desert, look into it, and figure out how you'll do it.
The last part is the hardest. Try not to worry about it. You've hiked before. You know what you're doing and you're comfortable with your gear. The trail will reveal itself to you one step at a time. What may seem like a massive undertaking will instantly collapse into a mile at a time. One water source to the next. One day at a time. One town to the next.
And when the trail doesn't reveal itself -- well, then you'll just have to find it.
