Having done a week-long backpacking on the AT solo, and just coming back from a week long Colorado backpacking trip (though with a friend) I would recommend the suggestions as to identifying beforehand travel routes, keeping others posted of progress (if possible), and having the correct gear (and pack) for changes in weather (especially places like Wyoming/Colorado). A day of hard rain can ruin a lot of plans and gear unless well-prepared. Having said that, there is nothing like backpacking alone, a wonderful experience.