The major problem with Batman v. Superman and Suicide Squad was the uneven nature of the films. They didn't feel singular. No offense to David Ayer or Zack Snyder but there didn't seem to a vision behind those films. This goes back to their being a lack of story. If Ben Affleck is really going to make The Batman stand out, if it's going to be worthy of the Christopher Nolan films, the story needs to be coherent. Already, the fact that The Batman has five writers (including Affleck), makes the ability to do this quite difficult. Screenwriting in a singular setting, where a writer is constantly fielding notes, is extremely difficult as often the notes are about as specific as an episode of Dancing With the Stars. In a group setting, where everybody is grousing over ideas and various egos need to be stroked, getting anything that resembles a vision is downright impossible. Ben Affleck needs to be the example here. He needs to figure out what the story is (if he hasn't already), and focus on that with a laser type ferocity. Again, he needs to become like The Dark Knight. Only this slash and burn approach will produce a movie with any substance. This isn't always the case. However, they are making The Batman here not Paul Blart 6.
Go method when putting on the suit.
This section focuses on how Ben Affleck plans to play Batman in The Batman. Remember everything Affleck did when he played the Caped Crusader in Batman v. Superman? Basically, except for a few scenes as Bruce Wayne, Affleck needs to jettison that portrayal entirely. Affleck needs to hole up as this character for the entirety of the shoot. On the set, people should call him Bruce. He should never casually stroll around in the Batsuit for ANY reason. If this means he spends the shoot in some form of seclusion (however, he still needs to interact with the cast -- I'll get to that shortly), then that is precisely what Ben needs to do. I am not sure how Christian Bale played Batman on the set, but I am sure that it was in a way that the other actors felt a sense of distance from him. As a viewer, I never really felt that distance from Affleck. As solid of an actor as he is, his portrayal in Batman v. Superman felt like just that, a portrayal. We can't see Ben Affleck in this portrayal of Batman. We need to see The Dark Knight. We need to see the tormented character who wants to do the right thing, but is constantly torn between the dark and the light. Ben Affleck can't be seen as playing that. He needs to be seen AS that.