I'm set to begin marathon preparation at the end of June. I've got a day planner in which every run I'll be doing over the 24 weeks of training is written down . I enjoy having the ability to look at any given day and know exactly how far and fast (speed is relative of course) I'm supposed to run. The structure will keep me from making excuses and needlessly moving workouts around - which I do now when I don't want to get out of bed.
Every book, magazine, and website I've read states that first time marathoners should not worry about a time goal. For me, the time goal is a large motivational factor. With that being the case, I've set three seperate goals. One for the best case scenario - perfect weather, great night sleep beforehand, no nagging injuries - which is a 3:30 finish time. My fallback time goals are 3:45 and 4:00. 3:30 is a pretty lofty goal, especially given my history of minor nagging injuries (foot and hip) and lack of experience running 26.2 miles at one time.
I'm using the month of June to increase the consistency of my runs. Over the past few months I've only averaged about 25 miles a week and didn't always get in a decent long run. This month I've structured each week similar to the first week of the official training program. This should help me make it through the first few weeks of marathon training a little easier.