6. Keep It Funny, But Keep The Horror
Evil Dead has slowly evolved into a horror-comedy. Evil Dead 2, in many respects, got the formula down perfectly. For every gag and hilarious scene, it had at least a little element of maddening horror. Sometimes, the two overlapped, and that made it all the better. Army of Darkness was much more of a comedy, but there were still some horror elements there, like demonic possession. Still, I'd like to have at least one scene in the sequel that leaves a few people uncomfortable. A scene can be so outrageously grotesque that it's funny, and so slapstick funny it borders onto horror. The best moments in this series walk that thin line.
5. Over-the-top Action
Each Evil Dead film has at least one great action scene. In Evil Dead, the fights were bloody and grotesque, and contained some very memorable moments, like the shovel-head chopping scene. Evil Dead 2 had some sillier fights, though the best is probably Ash vs. his own hand. Army of Darkness ended with all-out war. We need Ash to do something really crazy this time around. One element that can be explored is his missing hand. In the second film, they put a chainsaw on it. The third, a gauntlet. How about this time they put on a harpoon or bazooka? Or maybe four chainsaws? Army of Darkness's spin-offs explored the possibility of putting just about anything there. Perhaps have a fight where Ash tries to put new things in that slot to kill the deadites with each option more ridiculous than the last. I wouldn't mind seeing him kill a Deadite with a blender on his hand. So long as it's awesome and impractical, it works.