In 2006 I didn't really think to have a game plan, so since 2007 I've basically followed this routine and just added to it when HHN started doing more mazes:
1. Enter the park around early 7-ish and go directly to Terror Tram
(1.5). Depending on my group, probably eat something. Last year was the first time I ever ate inside the park for HHN, so for me it's optional.
2. Do Walking Dead (before WD it would be whatever House of Horrors maze, just to get it out of the way since it wouldn't be completely different)
3. Texas Chainsaw Massacre (or whatever maze(s) are on the Upper lot)
4. Halloween (or whatever Jurassic Park queue maze)
5. The Exorcist (or whatever Mummy queue maze)
6. Krampus
7. Freddy vs. Jason
8. American Horror Story
(9). If I'm in the mood, go on the rides. I have never done the shows in all the years I've gone so usually in the past after I finish the mazes, with VIP I would always repeat them, but not anymore now.
Last year I think I finished the mazes and Terror tram by 11:00-ish.