4. Study The Animated Series
Kind of gave it away already, didn't I? It doesn't make this point any less valid, though. Whilst I admit I think this would be the best possible ensemble for a JLA film - with maybe the exception of Hawkgirl - I can also admit that it doesn't have to be the definite cast to make the film work. However, what needs to be taken from this brilliant series is the constant variety of storylines, focusing on different characters and demonstrating superb chemistry. Those three things would practically guarantee a great film for the audience to enjoy. What this series proved way before The Avengers film was even a dream in the Marvel Studios was that all these amazing characters could work well together and not be too convoluted. The chemistry in particular in this series was an absolute joy to watch; every character's strengths and weaknesses were on show to full effect, providing both comedic and heartfelt moments that the live action JLA film will do extremely well to replicate. The events of Batman vs. Superman will be a key component to how Bats and Supes will interact with each other in this film. They aren't really great friends at the best of times, but there is that mutual respect for each other. This will no doubt help the JLA film give us some great tension (think Iron Man and Captain America in The Avengers) and team-building situations. If this can be spread throughout the rest of the team, it will be a joy to watch.