10. Slow Way Down
One of the main problems with the DCEU has been pointed out by fans time and time again - the movies are trying to advance everything too quickly.
They had the first movie of the series followed-up by the supposed big crossover event without any room to breathe. The equivalent would be the first Iron Man being followed-up by an Avengers movie. It just doesn’t make any sense.
Although it might seem counter-intuitive to try and take as long as possible, it will pay-off in the long-run when fans are dying to see the second part to a galaxy-wide event. Instead of rushing huge crossover movies, the DCEU should be world-building across multiple, smaller movies.
After all, why should the audience care about a world-ending event, when they know nothing about the world, who inhabits it and why they should care? If the DCEU took its time to develop its universe through fun and interesting movies, than a big team-up events would be all the sweeter.
There is no need to rush. The MCU only started to become big after The Avengers, an event which took 4 years, and several movies to build up to.