It sounds like this is for people trying to FINISH the thing. My opinion is that a) there's not much to know - you start running and run more and more then try it; b) the 'just finishing' market is pretty full - many books exist that include runs starting at 3 miles progressing to 10, then you try the half.
This dead horse does not need to be flogged any further. I clicked hoping to find a serious runner's resource for those of us who have no question at all about being able to run 13 or 14 miles without stopping and do so more than once a week. This market is smaller but is well represented on this forum so this post must not surprise you.