After you take an inventory, create a schedule of the project.
I really disagree on having a schedule or timetable. Do it as you like if not it will become a chore and you won't want anything to do with it. You'll end up loathing it and it will just sit there until you sell it for next to nothing just to get rid of it. All you need is to have a plan on a specific area you want to tackle. It doesn't matter how long it takes. When it starts to not be fun, stop for a bit or a day, whatever. When you come back it will be fun again. It's a hobby, keep it that way.
Bruce I hear you on that I had a friend who this happened to after awhile he hated working on his (sorry non GM)roadrunner and he finally sold it. I DO NOT WANT THIS TO HAPPEN TO ME